Class RenderingHints
- java.lang.Object
-
- java.awt.RenderingHints
public class RenderingHints extends Object implements Map<Object,Object>, Cloneable
The RenderingHints
class defines and manages collections of keys and associated values which allow an application to provide input into the choice of algorithms used by other classes which perform rendering and image manipulation services. The Graphics2D
class, and classes that implement BufferedImageOp
and RasterOp
all provide methods to get and possibly to set individual or groups of RenderingHints
keys and their associated values. When those implementations perform any rendering or image manipulation operations they should examine the values of any RenderingHints
that were requested by the caller and tailor the algorithms used accordingly and to the best of their ability.
Note that since these keys and values are hints, there is no requirement that a given implementation supports all possible choices indicated below or that it can respond to requests to modify its choice of algorithm. The values of the various hint keys may also interact such that while all variants of a given key are supported in one situation, the implementation may be more restricted when the values associated with other keys are modified. For example, some implementations may be able to provide several types of dithering when the antialiasing hint is turned off, but have little control over dithering when antialiasing is on. The full set of supported keys and hints may also vary by destination since runtimes may use different underlying modules to render to the screen, or to BufferedImage
objects, or while printing.
Implementations are free to ignore the hints completely, but should try to use an implementation algorithm that is as close as possible to the request. If an implementation supports a given algorithm when any value is used for an associated hint key, then minimally it must do so when the value for that key is the exact value that specifies the algorithm.
The keys used to control the hints are all special values that subclass the associated RenderingHints.Key
class. Many common hints are expressed below as static constants in this class, but the list is not meant to be exhaustive. Other hints may be created by other packages by defining new objects which subclass the Key
class and defining the associated values.
Nested Class Summary
Modifier and Type | Class | Description |
---|---|---|
static class | RenderingHints.Key | Defines the base type of all keys used along with the |
Nested classes/interfaces declared in interface java.util.Map
Map.Entry<K,V>
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static RenderingHints.Key | KEY_ALPHA_INTERPOLATION | Alpha interpolation hint key. |
static RenderingHints.Key | KEY_ANTIALIASING | Antialiasing hint key. |
static RenderingHints.Key | KEY_COLOR_RENDERING | Color rendering hint key. |
static RenderingHints.Key | KEY_DITHERING | Dithering hint key. |
static RenderingHints.Key | KEY_FRACTIONALMETRICS | Font fractional metrics hint key. |
static RenderingHints.Key | KEY_INTERPOLATION | Interpolation hint key. |
static RenderingHints.Key | KEY_RENDERING | Rendering hint key. |
static RenderingHints.Key | KEY_RESOLUTION_VARIANT | Image resolution variant hint key. |
static RenderingHints.Key | KEY_STROKE_CONTROL | Stroke normalization control hint key. |
static RenderingHints.Key | KEY_TEXT_ANTIALIASING | Text antialiasing hint key. |
static RenderingHints.Key | KEY_TEXT_LCD_CONTRAST | LCD text contrast rendering hint key. |
static Object | VALUE_ALPHA_INTERPOLATION_DEFAULT | Alpha interpolation hint value -- alpha blending algorithms are chosen by the implementation for a good tradeoff of performance vs. quality. |
static Object | VALUE_ALPHA_INTERPOLATION_QUALITY | Alpha interpolation hint value -- alpha blending algorithms are chosen with a preference for precision and visual quality. |
static Object | VALUE_ALPHA_INTERPOLATION_SPEED | Alpha interpolation hint value -- alpha blending algorithms are chosen with a preference for calculation speed. |
static Object | VALUE_ANTIALIAS_DEFAULT | Antialiasing hint value -- rendering is done with a default antialiasing mode chosen by the implementation. |
static Object | VALUE_ANTIALIAS_OFF | Antialiasing hint value -- rendering is done without antialiasing. |
static Object | VALUE_ANTIALIAS_ON | Antialiasing hint value -- rendering is done with antialiasing. |
static Object | VALUE_COLOR_RENDER_DEFAULT | Color rendering hint value -- perform color conversion calculations as chosen by the implementation to represent the best available tradeoff between performance and accuracy. |
static Object | VALUE_COLOR_RENDER_QUALITY | Color rendering hint value -- perform the color conversion calculations with the highest accuracy and visual quality. |
static Object | VALUE_COLOR_RENDER_SPEED | Color rendering hint value -- perform the fastest color conversion to the format of the output device. |
static Object | VALUE_DITHER_DEFAULT | Dithering hint value -- use a default for dithering chosen by the implementation. |
static Object | VALUE_DITHER_DISABLE | Dithering hint value -- do not dither when rendering geometry. |
static Object | VALUE_DITHER_ENABLE | Dithering hint value -- dither when rendering geometry, if needed. |
static Object | VALUE_FRACTIONALMETRICS_DEFAULT | Font fractional metrics hint value -- character glyphs are positioned with accuracy chosen by the implementation. |
static Object | VALUE_FRACTIONALMETRICS_OFF | Font fractional metrics hint value -- character glyphs are positioned with advance widths rounded to pixel boundaries. |
static Object | VALUE_FRACTIONALMETRICS_ON | Font fractional metrics hint value -- character glyphs are positioned with sub-pixel accuracy. |
static Object | VALUE_INTERPOLATION_BICUBIC | Interpolation hint value -- the color samples of 9 nearby integer coordinate samples in the image are interpolated using a cubic function in both |
static Object | VALUE_INTERPOLATION_BILINEAR | Interpolation hint value -- the color samples of the 4 nearest neighboring integer coordinate samples in the image are interpolated linearly to produce a color sample. |
static Object | VALUE_INTERPOLATION_NEAREST_NEIGHBOR | Interpolation hint value -- the color sample of the nearest neighboring integer coordinate sample in the image is used. |
static Object | VALUE_RENDER_DEFAULT | Rendering hint value -- rendering algorithms are chosen by the implementation for a good tradeoff of performance vs. quality. |
static Object | VALUE_RENDER_QUALITY | Rendering hint value -- rendering algorithms are chosen with a preference for output quality. |
static Object | VALUE_RENDER_SPEED | Rendering hint value -- rendering algorithms are chosen with a preference for output speed. |
static Object | VALUE_RESOLUTION_VARIANT_BASE | Image resolution variant hint value -- the standard resolution of an image is always used. |
static Object | VALUE_RESOLUTION_VARIANT_DEFAULT | Image resolution variant hint value -- an image resolution variant is chosen based on a default heuristic which may depend on the policies of the platform |
static Object | VALUE_RESOLUTION_VARIANT_DPI_FIT | Image resolution variant hint value -- an image resolution variant is chosen based only on the DPI of the screen. |
static Object | VALUE_RESOLUTION_VARIANT_SIZE_FIT | Image resolution variant hint value -- an image resolution variant is chosen based on the DPI of the screen and the transform in the Graphics2D context. |
static Object | VALUE_STROKE_DEFAULT | Stroke normalization control hint value -- geometry may be modified or left pure depending on the tradeoffs in a given implementation. |
static Object | VALUE_STROKE_NORMALIZE | Stroke normalization control hint value -- geometry should be normalized to improve uniformity or spacing of lines and overall aesthetics. |
static Object | VALUE_STROKE_PURE | Stroke normalization control hint value -- geometry should be left unmodified and rendered with sub-pixel accuracy. |
static Object | VALUE_TEXT_ANTIALIAS_DEFAULT | Text antialiasing hint value -- text rendering is done according to the |
static Object | VALUE_TEXT_ANTIALIAS_GASP | Text antialiasing hint value -- text rendering is requested to use information in the font resource which specifies for each point size whether to apply |
static Object | VALUE_TEXT_ANTIALIAS_LCD_HBGR | Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixels in order from display left to right of B,G,R such that the horizontal subpixel resolution is three times that of the full pixel horizontal resolution (HBGR). |
static Object | VALUE_TEXT_ANTIALIAS_LCD_HRGB | Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixels in order from display left to right of R,G,B such that the horizontal subpixel resolution is three times that of the full pixel horizontal resolution (HRGB). |
static Object | VALUE_TEXT_ANTIALIAS_LCD_VBGR | Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixel organisation from display top to bottom of B,G,R such that the vertical subpixel resolution is three times that of the full pixel vertical resolution (VBGR). |
static Object | VALUE_TEXT_ANTIALIAS_LCD_VRGB | Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixel organisation from display top to bottom of R,G,B such that the vertical subpixel resolution is three times that of the full pixel vertical resolution (VRGB). |
static Object | VALUE_TEXT_ANTIALIAS_OFF | Text antialiasing hint value -- text rendering is done without any form of antialiasing. |
static Object | VALUE_TEXT_ANTIALIAS_ON | Text antialiasing hint value -- text rendering is done with some form of antialiasing. |
Constructor Summary
Constructor | Description |
---|---|
RenderingHints(RenderingHints.Key key,
Object value) | Constructs a new object with the specified key/value pair. |
RenderingHints(Map<RenderingHints.Key,?> init) | Constructs a new object with keys and values initialized from the specified Map object which may be null. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | add(RenderingHints hints) | Adds all of the keys and corresponding values from the specified |
void | clear() | Clears this |
Object | clone() | Creates a clone of this |
boolean | containsKey(Object key) | Returns |
boolean | containsValue(Object value) | Returns true if this RenderingHints maps one or more keys to the specified value. |
Set<Map.Entry<Object,Object>> | entrySet() | Returns a |
boolean | equals(Object o) | Compares the specified |
Object | get(Object key) | Returns the value to which the specified key is mapped. |
int | hashCode() | Returns the hash code value for this |
boolean | isEmpty() | Returns |
Set<Object> | keySet() | Returns a |
Object | put(Object key,
Object value) | Maps the specified |
void | putAll(Map<?,?> m) | Copies all of the mappings from the specified |
Object | remove(Object key) | Removes the key and its corresponding value from this |
int | size() | Returns the number of key-value mappings in this |
String | toString() | Returns a rather long string representation of the hashmap which contains the mappings of keys to values for this |
Collection<Object> | values() | Returns a |
Methods declared in class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
Methods declared in interface java.util.Map
compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll
Field Detail
KEY_ANTIALIASING
public static final RenderingHints.Key KEY_ANTIALIASING
Antialiasing hint key. The ANTIALIASING
hint controls whether or not the geometry rendering methods of a Graphics2D
object will attempt to reduce aliasing artifacts along the edges of shapes.
A typical antialiasing algorithm works by blending the existing colors of the pixels along the boundary of a shape with the requested fill paint according to the estimated partial pixel coverage of the shape.
The allowable values for this hint are
VALUE_ANTIALIAS_ON
public static final Object VALUE_ANTIALIAS_ON
Antialiasing hint value -- rendering is done with antialiasing.
- See Also:
KEY_ANTIALIASING
VALUE_ANTIALIAS_OFF
public static final Object VALUE_ANTIALIAS_OFF
Antialiasing hint value -- rendering is done without antialiasing.
- See Also:
KEY_ANTIALIASING
VALUE_ANTIALIAS_DEFAULT
public static final Object VALUE_ANTIALIAS_DEFAULT
Antialiasing hint value -- rendering is done with a default antialiasing mode chosen by the implementation.
- See Also:
KEY_ANTIALIASING
KEY_RENDERING
public static final RenderingHints.Key KEY_RENDERING
Rendering hint key. The RENDERING
hint is a general hint that provides a high level recommendation as to whether to bias algorithm choices more for speed or quality when evaluating tradeoffs. This hint could be consulted for any rendering or image manipulation operation, but decisions will usually honor other, more specific hints in preference to this hint.
The allowable values for this hint are
VALUE_RENDER_SPEED
public static final Object VALUE_RENDER_SPEED
Rendering hint value -- rendering algorithms are chosen with a preference for output speed.
- See Also:
KEY_RENDERING
VALUE_RENDER_QUALITY
public static final Object VALUE_RENDER_QUALITY
Rendering hint value -- rendering algorithms are chosen with a preference for output quality.
- See Also:
KEY_RENDERING
VALUE_RENDER_DEFAULT
public static final Object VALUE_RENDER_DEFAULT
Rendering hint value -- rendering algorithms are chosen by the implementation for a good tradeoff of performance vs. quality.
- See Also:
KEY_RENDERING
KEY_DITHERING
public static final RenderingHints.Key KEY_DITHERING
Dithering hint key. The DITHERING
hint controls how closely to approximate a color when storing into a destination with limited color resolution.
Some rendering destinations may support a limited number of color choices which may not be able to accurately represent the full spectrum of colors that can result during rendering operations. For such a destination the DITHERING
hint controls whether rendering is done with a flat solid fill of a single pixel value which is the closest supported color to what was requested, or whether shapes will be filled with a pattern of colors which combine to better approximate that color.
The allowable values for this hint are
VALUE_DITHER_DISABLE
public static final Object VALUE_DITHER_DISABLE
Dithering hint value -- do not dither when rendering geometry.
- See Also:
KEY_DITHERING
VALUE_DITHER_ENABLE
public static final Object VALUE_DITHER_ENABLE
Dithering hint value -- dither when rendering geometry, if needed.
- See Also:
KEY_DITHERING
VALUE_DITHER_DEFAULT
public static final Object VALUE_DITHER_DEFAULT
Dithering hint value -- use a default for dithering chosen by the implementation.
- See Also:
KEY_DITHERING
KEY_TEXT_ANTIALIASING
public static final RenderingHints.Key KEY_TEXT_ANTIALIASING
Text antialiasing hint key. The TEXT_ANTIALIASING
hint can control the use of antialiasing algorithms for text independently of the choice used for shape rendering. Often an application may want to use antialiasing for text only and not for other shapes. Additionally, the algorithms for reducing the aliasing artifacts for text are often more sophisticated than those that have been developed for general rendering so this hint key provides additional values which can control the choices of some of those text-specific algorithms. If left in the DEFAULT
state, this hint will generally defer to the value of the regular KEY_ANTIALIASING
hint key.
The allowable values for this hint are
VALUE_TEXT_ANTIALIAS_ON
public static final Object VALUE_TEXT_ANTIALIAS_ON
Text antialiasing hint value -- text rendering is done with some form of antialiasing.
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_OFF
public static final Object VALUE_TEXT_ANTIALIAS_OFF
Text antialiasing hint value -- text rendering is done without any form of antialiasing.
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_DEFAULT
public static final Object VALUE_TEXT_ANTIALIAS_DEFAULT
Text antialiasing hint value -- text rendering is done according to the KEY_ANTIALIASING
hint or a default chosen by the implementation.
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_GASP
public static final Object VALUE_TEXT_ANTIALIAS_GASP
Text antialiasing hint value -- text rendering is requested to use information in the font resource which specifies for each point size whether to apply VALUE_TEXT_ANTIALIAS_ON
or VALUE_TEXT_ANTIALIAS_OFF
.
TrueType fonts typically provide this information in the 'gasp' table. In the absence of this information, the behaviour for a particular font and size is determined by implementation defaults.
Note:A font designer will typically carefully hint a font for the most common user interface point sizes. Consequently the 'gasp' table will likely specify to use only hinting at those sizes and not "smoothing". So in many cases the resulting text display is equivalent to VALUE_TEXT_ANTIALIAS_OFF
. This may be unexpected but is correct.
Logical fonts which are composed of multiple physical fonts will for consistency will use the setting most appropriate for the overall composite font.
- Since:
- 1.6
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_LCD_HRGB
public static final Object VALUE_TEXT_ANTIALIAS_LCD_HRGB
Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixels in order from display left to right of R,G,B such that the horizontal subpixel resolution is three times that of the full pixel horizontal resolution (HRGB). This is the most common configuration. Selecting this hint for displays with one of the other LCD subpixel configurations will likely result in unfocused text.
Notes:
An implementation when choosing whether to apply any of the LCD text hint values may take into account factors including requiring color depth of the destination to be at least 15 bits per pixel (ie 5 bits per color component), characteristics of a font such as whether embedded bitmaps may produce better results, or when displaying to a non-local networked display device enabling it only if suitable protocols are available, or ignoring the hint if performing very high resolution rendering or the target device is not appropriate: eg when printing.
These hints can equally be applied when rendering to software images, but these images may not then be suitable for general export, as the text will have been rendered appropriately for a specific subpixel organisation. Also lossy images are not a good choice, nor image formats such as GIF which have limited colors. So unless the image is destined solely for rendering on a display device with the same configuration, some other text anti-aliasing hint such as VALUE_TEXT_ANTIALIAS_ON
may be a better choice.
Selecting a value which does not match the LCD display in use will likely lead to a degradation in text quality. On display devices (ie CRTs) which do not have the same characteristics as LCD displays, the overall effect may appear similar to standard text anti-aliasing, but the quality may be degraded by color distortion. Analog connected LCD displays may also show little advantage over standard text-antialiasing and be similar to CRTs.
In other words for the best results use an LCD display with a digital display connector and specify the appropriate sub-pixel configuration.
- Since:
- 1.6
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_LCD_HBGR
public static final Object VALUE_TEXT_ANTIALIAS_LCD_HBGR
Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixels in order from display left to right of B,G,R such that the horizontal subpixel resolution is three times that of the full pixel horizontal resolution (HBGR). This is a much less common configuration than HRGB. Selecting this hint for displays with one of the other LCD subpixel configurations will likely result in unfocused text. See VALUE_TEXT_ANTIALIAS_LCD_HRGB
, for more information on when this hint is applied.
- Since:
- 1.6
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_LCD_VRGB
public static final Object VALUE_TEXT_ANTIALIAS_LCD_VRGB
Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixel organisation from display top to bottom of R,G,B such that the vertical subpixel resolution is three times that of the full pixel vertical resolution (VRGB). Vertical orientation is very uncommon and probably mainly useful for a physically rotated display. Selecting this hint for displays with one of the other LCD subpixel configurations will likely result in unfocused text. See VALUE_TEXT_ANTIALIAS_LCD_HRGB
, for more information on when this hint is applied.
- Since:
- 1.6
- See Also:
KEY_TEXT_ANTIALIASING
VALUE_TEXT_ANTIALIAS_LCD_VBGR
public static final Object VALUE_TEXT_ANTIALIAS_LCD_VBGR
Text antialiasing hint value -- request that text be displayed optimised for an LCD display with subpixel organisation from display top to bottom of B,G,R such that the vertical subpixel resolution is three times that of the full pixel vertical resolution (VBGR). Vertical orientation is very uncommon and probably mainly useful for a physically rotated display. Selecting this hint for displays with one of the other LCD subpixel configurations will likely result in unfocused text. See VALUE_TEXT_ANTIALIAS_LCD_HRGB
, for more information on when this hint is applied.
- Since:
- 1.6
- See Also:
KEY_TEXT_ANTIALIASING
KEY_TEXT_LCD_CONTRAST
public static final RenderingHints.Key KEY_TEXT_LCD_CONTRAST
LCD text contrast rendering hint key. The value is an Integer
object which is used as a text contrast adjustment when used in conjunction with an LCD text anti-aliasing hint such as VALUE_TEXT_ANTIALIAS_LCD_HRGB
.
- Values should be a positive integer in the range 100 to 250.
- A lower value (eg 100) corresponds to higher contrast text when displaying dark text on a light background.
- A higher value (eg 200) corresponds to lower contrast text when displaying dark text on a light background.
- A typical useful value is in the narrow range 140-180.
- If no value is specified, a system or implementation default value will be applied.
- Since:
- 1.6
- See Also:
KEY_TEXT_ANTIALIASING
KEY_FRACTIONALMETRICS
public static final RenderingHints.Key KEY_FRACTIONALMETRICS
Font fractional metrics hint key. The FRACTIONALMETRICS
hint controls whether the positioning of individual character glyphs takes into account the sub-pixel accuracy of the scaled character advances of the font or whether such advance vectors are rounded to an integer number of whole device pixels. This hint only recommends how much accuracy should be used to position the glyphs and does not specify or recommend whether or not the actual rasterization or pixel bounds of the glyph should be modified to match.
Rendering text to a low resolution device like a screen will necessarily involve a number of rounding operations as the high quality and very precise definition of the shape and metrics of the character glyphs must be matched to discrete device pixels. Ideally the positioning of glyphs during text layout would be calculated by scaling the design metrics in the font according to the point size, but then the scaled advance width will not necessarily be an integer number of pixels. If the glyphs are positioned with sub-pixel accuracy according to these scaled design metrics then the rasterization would ideally need to be adjusted for each possible sub-pixel origin.
Unfortunately, scaling each glyph customized to its exact subpixel origin during text layout would be prohibitively expensive so a simplified system based on integer device positions is typically used to lay out the text. The rasterization of the glyph and the scaled advance width are both adjusted together to yield text that looks good at device resolution and has consistent integer pixel distances between glyphs that help the glyphs look uniformly and consistently spaced and readable.
This process of rounding advance widths for rasterized glyphs to integer distances means that the character density and the overall length of a string of text will be different from the theoretical design measurements due to the accumulation of a series of small differences in the adjusted widths of each glyph. The specific differences will be different for each glyph, some being wider and some being narrower than their theoretical design measurements. Thus the overall difference in character density and length will vary by a number of factors including the font, the specific device resolution being targeted, and the glyphs chosen to represent the string being rendered. As a result, rendering the same string at multiple device resolutions can yield widely varying metrics for whole strings.
When FRACTIONALMETRICS
are enabled, the true font design metrics are scaled by the point size and used for layout with sub-pixel accuracy. The average density of glyphs and total length of a long string of characters will therefore more closely match the theoretical design of the font, but readability may be affected since individual pairs of characters may not always appear to be consistent distances apart depending on how the sub-pixel accumulation of the glyph origins meshes with the device pixel grid. Enabling this hint may be desirable when text layout is being performed that must be consistent across a wide variety of output resolutions. Specifically, this hint may be desirable in situations where the layout of text is being previewed on a low resolution device like a screen for output that will eventually be rendered on a high resolution printer or typesetting device.
When disabled, the scaled design metrics are rounded or adjusted to integer distances for layout. The distances between any specific pair of glyphs will be more uniform on the device, but the density and total length of long strings may no longer match the theoretical intentions of the font designer. Disabling this hint will typically produce more readable results on low resolution devices like computer monitors.
The allowable values for this key are
VALUE_FRACTIONALMETRICS_OFF
public static final Object VALUE_FRACTIONALMETRICS_OFF
Font fractional metrics hint value -- character glyphs are positioned with advance widths rounded to pixel boundaries.
- See Also:
KEY_FRACTIONALMETRICS
VALUE_FRACTIONALMETRICS_ON
public static final Object VALUE_FRACTIONALMETRICS_ON
Font fractional metrics hint value -- character glyphs are positioned with sub-pixel accuracy.
- See Also:
KEY_FRACTIONALMETRICS
VALUE_FRACTIONALMETRICS_DEFAULT
public static final Object VALUE_FRACTIONALMETRICS_DEFAULT
Font fractional metrics hint value -- character glyphs are positioned with accuracy chosen by the implementation.
- See Also:
KEY_FRACTIONALMETRICS
KEY_INTERPOLATION
public static final RenderingHints.Key KEY_INTERPOLATION
Interpolation hint key. The INTERPOLATION
hint controls how image pixels are filtered or resampled during an image rendering operation.
Implicitly images are defined to provide color samples at integer coordinate locations. When images are rendered upright with no scaling onto a destination, the choice of which image pixels map to which device pixels is obvious and the samples at the integer coordinate locations in the image are transferred to the pixels at the corresponding integer locations on the device pixel grid one for one. When images are rendered in a scaled, rotated, or otherwise transformed coordinate system, then the mapping of device pixel coordinates back to the image can raise the question of what color sample to use for the continuous coordinates that lie between the integer locations of the provided image samples. Interpolation algorithms define functions which provide a color sample for any continuous coordinate in an image based on the color samples at the surrounding integer coordinates.
The allowable values for this hint are
VALUE_INTERPOLATION_NEAREST_NEIGHBOR
public static final Object VALUE_INTERPOLATION_NEAREST_NEIGHBOR
Interpolation hint value -- the color sample of the nearest neighboring integer coordinate sample in the image is used. Conceptually the image is viewed as a grid of unit-sized square regions of color centered around the center of each image pixel.
As the image is scaled up, it will look correspondingly blocky. As the image is scaled down, the colors for source pixels will be either used unmodified, or skipped entirely in the output representation.
- See Also:
KEY_INTERPOLATION
VALUE_INTERPOLATION_BILINEAR
public static final Object VALUE_INTERPOLATION_BILINEAR
Interpolation hint value -- the color samples of the 4 nearest neighboring integer coordinate samples in the image are interpolated linearly to produce a color sample. Conceptually the image is viewed as a set of infinitely small point color samples which have value only at the centers of integer coordinate pixels and the space between those pixel centers is filled with linear ramps of colors that connect adjacent discrete samples in a straight line.
As the image is scaled up, there are no blocky edges between the colors in the image as there are with NEAREST_NEIGHBOR
, but the blending may show some subtle discontinuities along the horizontal and vertical edges that line up with the samples caused by a sudden change in the slope of the interpolation from one side of a sample to the other. As the image is scaled down, more image pixels have their color samples represented in the resulting output since each output pixel receives color information from up to 4 image pixels.
- See Also:
KEY_INTERPOLATION
VALUE_INTERPOLATION_BICUBIC
public static final Object VALUE_INTERPOLATION_BICUBIC
Interpolation hint value -- the color samples of 9 nearby integer coordinate samples in the image are interpolated using a cubic function in both X
and Y
to produce a color sample. Conceptually the view of the image is very similar to the view used in the BILINEAR
algorithm except that the ramps of colors that connect between the samples are curved and have better continuity of slope as they cross over between sample boundaries.
As the image is scaled up, there are no blocky edges and the interpolation should appear smoother and with better depictions of any edges in the original image than with BILINEAR
. As the image is scaled down, even more of the original color samples from the original image will have their color information carried through and represented.
- See Also:
KEY_INTERPOLATION
KEY_ALPHA_INTERPOLATION
public static final RenderingHints.Key KEY_ALPHA_INTERPOLATION
Alpha interpolation hint key. The ALPHA_INTERPOLATION
hint is a general hint that provides a high level recommendation as to whether to bias alpha blending algorithm choices more for speed or quality when evaluating tradeoffs.
This hint could control the choice of alpha blending calculations that sacrifice some precision to use fast lookup tables or lower precision SIMD instructions. This hint could also control whether or not the color and alpha values are converted into a linear color space during the calculations for a more linear visual effect at the expense of additional per-pixel calculations.
The allowable values for this hint are
VALUE_ALPHA_INTERPOLATION_SPEED
public static final Object VALUE_ALPHA_INTERPOLATION_SPEED
Alpha interpolation hint value -- alpha blending algorithms are chosen with a preference for calculation speed.
- See Also:
KEY_ALPHA_INTERPOLATION
VALUE_ALPHA_INTERPOLATION_QUALITY
public static final Object VALUE_ALPHA_INTERPOLATION_QUALITY
Alpha interpolation hint value -- alpha blending algorithms are chosen with a preference for precision and visual quality.
- See Also:
KEY_ALPHA_INTERPOLATION
VALUE_ALPHA_INTERPOLATION_DEFAULT
public static final Object VALUE_ALPHA_INTERPOLATION_DEFAULT
Alpha interpolation hint value -- alpha blending algorithms are chosen by the implementation for a good tradeoff of performance vs. quality.
- See Also:
KEY_ALPHA_INTERPOLATION
KEY_COLOR_RENDERING
public static final RenderingHints.Key KEY_COLOR_RENDERING
Color rendering hint key. The COLOR_RENDERING
hint controls the accuracy of approximation and conversion when storing colors into a destination image or surface.
When a rendering or image manipulation operation produces a color value that must be stored into a destination, it must first convert that color into a form suitable for storing into the destination image or surface. Minimally, the color components must be converted to bit representations and ordered in the correct order or an index into a color lookup table must be chosen before the data can be stored into the destination memory. Without this minimal conversion, the data in the destination would likely represent random, incorrect or possibly even unsupported values. Algorithms to quickly convert the results of rendering operations into the color format of most common destinations are well known and fairly optimal to execute.
Simply performing the most basic color format conversion to store colors into a destination can potentially ignore a difference in the calibration of the ColorSpace
of the source and destination or other factors such as the linearity of the gamma correction. Unless the source and destination ColorSpace
are identical, to correctly perform a rendering operation with the most care taken for the accuracy of the colors being represented, the source colors should be converted to a device independent ColorSpace
and the results then converted back to the destination ColorSpace
. Furthermore, if calculations such as the blending of multiple source colors are to be performed during the rendering operation, greater visual clarity can be achieved if the intermediate device independent ColorSpace
is chosen to have a linear relationship between the values being calculated and the perception of the human eye to the response curves of the output device.
The allowable values for this hint are
VALUE_COLOR_RENDER_SPEED
public static final Object VALUE_COLOR_RENDER_SPEED
Color rendering hint value -- perform the fastest color conversion to the format of the output device.
- See Also:
KEY_COLOR_RENDERING
VALUE_COLOR_RENDER_QUALITY
public static final Object VALUE_COLOR_RENDER_QUALITY
Color rendering hint value -- perform the color conversion calculations with the highest accuracy and visual quality.
- See Also:
KEY_COLOR_RENDERING
VALUE_COLOR_RENDER_DEFAULT
public static final Object VALUE_COLOR_RENDER_DEFAULT
Color rendering hint value -- perform color conversion calculations as chosen by the implementation to represent the best available tradeoff between performance and accuracy.
- See Also:
KEY_COLOR_RENDERING
KEY_STROKE_CONTROL
public static final RenderingHints.Key KEY_STROKE_CONTROL
Stroke normalization control hint key. The STROKE_CONTROL
hint controls whether a rendering implementation should or is allowed to modify the geometry of rendered shapes for various purposes.
Some implementations may be able to use an optimized platform rendering library which may be faster than traditional software rendering algorithms on a given platform, but which may also not support floating point coordinates. Some implementations may also have sophisticated algorithms which perturb the coordinates of a path so that wide lines appear more uniform in width and spacing.
If an implementation performs any type of modification or "normalization" of a path, it should never move the coordinates by more than half a pixel in any direction.
The allowable values for this hint are
- Since:
- 1.3
VALUE_STROKE_DEFAULT
public static final Object VALUE_STROKE_DEFAULT
Stroke normalization control hint value -- geometry may be modified or left pure depending on the tradeoffs in a given implementation. Typically this setting allows an implementation to use a fast integer coordinate based platform rendering library, but does not specifically request normalization for uniformity or aesthetics.
- Since:
- 1.3
- See Also:
KEY_STROKE_CONTROL
VALUE_STROKE_NORMALIZE
public static final Object VALUE_STROKE_NORMALIZE
Stroke normalization control hint value -- geometry should be normalized to improve uniformity or spacing of lines and overall aesthetics. Note that different normalization algorithms may be more successful than others for given input paths.
- Since:
- 1.3
- See Also:
KEY_STROKE_CONTROL
VALUE_STROKE_PURE
public static final Object VALUE_STROKE_PURE
Stroke normalization control hint value -- geometry should be left unmodified and rendered with sub-pixel accuracy.
- Since:
- 1.3
- See Also:
KEY_STROKE_CONTROL
KEY_RESOLUTION_VARIANT
public static final RenderingHints.Key KEY_RESOLUTION_VARIANT
Image resolution variant hint key. The RESOLUTION_VARIANT
hint controls which image resolution variant should be chosen for image drawing.
-
VALUE_RESOLUTION_VARIANT_DEFAULT
-
VALUE_RESOLUTION_VARIANT_BASE
-
VALUE_RESOLUTION_VARIANT_SIZE_FIT
-
VALUE_RESOLUTION_VARIANT_DPI_FIT
- Since:
- 9
VALUE_RESOLUTION_VARIANT_DEFAULT
public static final Object VALUE_RESOLUTION_VARIANT_DEFAULT
Image resolution variant hint value -- an image resolution variant is chosen based on a default heuristic which may depend on the policies of the platform
- Since:
- 9
- See Also:
KEY_RESOLUTION_VARIANT
VALUE_RESOLUTION_VARIANT_BASE
public static final Object VALUE_RESOLUTION_VARIANT_BASE
Image resolution variant hint value -- the standard resolution of an image is always used.
- Since:
- 9
- See Also:
KEY_RESOLUTION_VARIANT
VALUE_RESOLUTION_VARIANT_SIZE_FIT
public static final Object VALUE_RESOLUTION_VARIANT_SIZE_FIT
Image resolution variant hint value -- an image resolution variant is chosen based on the DPI of the screen and the transform in the Graphics2D context.
- Since:
- 9
- See Also:
KEY_RESOLUTION_VARIANT
VALUE_RESOLUTION_VARIANT_DPI_FIT
public static final Object VALUE_RESOLUTION_VARIANT_DPI_FIT
Image resolution variant hint value -- an image resolution variant is chosen based only on the DPI of the screen.
- Since:
- 9
- See Also:
KEY_RESOLUTION_VARIANT
Constructor Detail
RenderingHints
public RenderingHints(Map<RenderingHints.Key,?> init)
Constructs a new object with keys and values initialized from the specified Map object which may be null.
- Parameters:
-
init
- a map of key/value pairs to initialize the hints or null if the object should be empty
RenderingHints
public RenderingHints(RenderingHints.Key key, Object value)
Constructs a new object with the specified key/value pair.
- Parameters:
-
key
- the key of the particular hint property -
value
- the value of the hint property specified withkey
Method Detail
size
public int size()
Returns the number of key-value mappings in this RenderingHints
.
- Specified by:
-
size
in interfaceMap<Object,Object>
- Returns:
- the number of key-value mappings in this
RenderingHints
.
isEmpty
public boolean isEmpty()
Returns true
if this RenderingHints
contains no key-value mappings.
- Specified by:
-
isEmpty
in interfaceMap<Object,Object>
- Returns:
-
true
if thisRenderingHints
contains no key-value mappings.
containsKey
public boolean containsKey(Object key)
Returns true
if this RenderingHints
contains a mapping for the specified key.
- Specified by:
-
containsKey
in interfaceMap<Object,Object>
- Parameters:
-
key
- key whose presence in thisRenderingHints
is to be tested. - Returns:
-
true
if thisRenderingHints
contains a mapping for the specified key. - Throws:
-
ClassCastException
- if the key can not be cast toRenderingHints.Key
containsValue
public boolean containsValue(Object value)
Returns true if this RenderingHints maps one or more keys to the specified value. More formally, returns true
if and only if this RenderingHints
contains at least one mapping to a value v
such that
(value==null ? v==null : value.equals(v)). This operation will probably require time linear in the
RenderingHints
size for most implementations of RenderingHints
. - Specified by:
-
containsValue
in interfaceMap<Object,Object>
- Parameters:
-
value
- value whose presence in thisRenderingHints
is to be tested. - Returns:
-
true
if thisRenderingHints
maps one or more keys to the specified value.
get
public Object get(Object key)
Returns the value to which the specified key is mapped.
- Specified by:
-
get
in interfaceMap<Object,Object>
- Parameters:
-
key
- a rendering hint key - Returns:
- the value to which the key is mapped in this object or
null
if the key is not mapped to any value in this object. - Throws:
-
ClassCastException
- if the key can not be cast toRenderingHints.Key
- See Also:
put(Object, Object)
put
public Object put(Object key, Object value)
Maps the specified key
to the specified value
in this RenderingHints
object. Neither the key nor the value can be null
. The value can be retrieved by calling the get
method with a key that is equal to the original key.
- Specified by:
-
put
in interfaceMap<Object,Object>
- Parameters:
-
key
- the rendering hint key. -
value
- the rendering hint value. - Returns:
- the previous value of the specified key in this object or
null
if it did not have one. - Throws:
-
NullPointerException
- if the key isnull
. -
ClassCastException
- if the key can not be cast toRenderingHints.Key
-
IllegalArgumentException
- if theKey.isCompatibleValue()
method of the specified key returns false for the specified value - See Also:
get(Object)
add
public void add(RenderingHints hints)
Adds all of the keys and corresponding values from the specified RenderingHints
object to this RenderingHints
object. Keys that are present in this RenderingHints
object, but not in the specified RenderingHints
object are not affected.
- Parameters:
-
hints
- the set of key/value pairs to be added to thisRenderingHints
object
clear
public void clear()
Clears this RenderingHints
object of all key/value pairs.
remove
public Object remove(Object key)
Removes the key and its corresponding value from this RenderingHints
object. This method does nothing if the key is not in this RenderingHints
object.
- Specified by:
-
remove
in interfaceMap<Object,Object>
- Parameters:
-
key
- the rendering hints key that needs to be removed - Returns:
- the value to which the key had previously been mapped in this
RenderingHints
object, ornull
if the key did not have a mapping. - Throws:
-
ClassCastException
- if the key can not be cast toRenderingHints.Key
putAll
public void putAll(Map<?,?> m)
Copies all of the mappings from the specified Map
to this RenderingHints
. These mappings replace any mappings that this RenderingHints
had for any of the keys currently in the specified Map
.
- Specified by:
-
putAll
in interfaceMap<Object,Object>
- Parameters:
-
m
- the specifiedMap
- Throws:
-
ClassCastException
- class of a key or value in the specifiedMap
prevents it from being stored in thisRenderingHints
. -
IllegalArgumentException
- some aspect of a key or value in the specifiedMap
prevents it from being stored in thisRenderingHints
.
keySet
public Set<Object> keySet()
Returns a Set
view of the Keys contained in this RenderingHints
. The Set is backed by the RenderingHints
, so changes to the RenderingHints
are reflected in the Set
, and vice-versa. If the RenderingHints
is modified while an iteration over the Set
is in progress, the results of the iteration are undefined. The Set
supports element removal, which removes the corresponding mapping from the RenderingHints
, via the Iterator.remove
, Set.remove
, removeAll retainAll
, and clear
operations. It does not support the add
or addAll
operations.
- Specified by:
-
keySet
in interfaceMap<Object,Object>
- Returns:
- a
Set
view of the keys contained in thisRenderingHints
.
values
public Collection<Object> values()
Returns a Collection
view of the values contained in this RenderingHints
. The Collection
is backed by the RenderingHints
, so changes to the RenderingHints
are reflected in the Collection
, and vice-versa. If the RenderingHints
is modified while an iteration over the Collection
is in progress, the results of the iteration are undefined. The Collection
supports element removal, which removes the corresponding mapping from the RenderingHints
, via the Iterator.remove
, Collection.remove
, removeAll
, retainAll
and clear
operations. It does not support the add
or addAll
operations.
- Specified by:
-
values
in interfaceMap<Object,Object>
- Returns:
- a
Collection
view of the values contained in thisRenderingHints
.
entrySet
public Set<Map.Entry<Object,Object>> entrySet()
Returns a Set
view of the mappings contained in this RenderingHints
. Each element in the returned Set
is a Map.Entry
. The Set
is backed by the RenderingHints
, so changes to the RenderingHints
are reflected in the Set
, and vice-versa. If the RenderingHints
is modified while while an iteration over the Set
is in progress, the results of the iteration are undefined.
The entrySet returned from a RenderingHints
object is not modifiable.
- Specified by:
-
entrySet
in interfaceMap<Object,Object>
- Returns:
- a
Set
view of the mappings contained in thisRenderingHints
.
equals
public boolean equals(Object o)
Compares the specified Object
with this RenderingHints
for equality. Returns true
if the specified object is also a Map
and the two Map
objects represent the same mappings. More formally, two Map
objects t1
and t2
represent the same mappings if t1.keySet().equals(t2.keySet())
and for every key k
in t1.keySet()
,
(t1.get(k)==null ? t2.get(k)==null : t1.get(k).equals(t2.get(k))). This ensures that the
equals
method works properly across different implementations of the Map
interface. - Specified by:
-
equals
in interfaceMap<Object,Object>
- Overrides:
-
equals
in classObject
- Parameters:
-
o
-Object
to be compared for equality with thisRenderingHints
. - Returns:
-
true
if the specifiedObject
is equal to thisRenderingHints
. - See Also:
-
Object.hashCode()
,HashMap
hashCode
public int hashCode()
Returns the hash code value for this RenderingHints
. The hash code of a RenderingHints
is defined to be the sum of the hashCodes of each Entry
in the RenderingHints
object's entrySet view. This ensures that t1.equals(t2)
implies that t1.hashCode()==t2.hashCode()
for any two Map
objects t1
and t2
, as required by the general contract of Object.hashCode
.
- Specified by:
-
hashCode
in interfaceMap<Object,Object>
- Overrides:
-
hashCode
in classObject
- Returns:
- the hash code value for this
RenderingHints
. - See Also:
-
Map.Entry.hashCode()
,Object.hashCode()
,Object.equals(Object)
,equals(Object)
clone
public Object clone()
Creates a clone of this RenderingHints
object that has the same contents as this RenderingHints
object.
toString
public String toString()
Returns a rather long string representation of the hashmap which contains the mappings of keys to values for this RenderingHints
object.