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## com.mxgraph.util.png
Class mxPngEncodeParam

    java.lang.Object
      com.mxgraph.util.png.mxPngEncodeParam

Direct Known Subclasses:
  mxPngEncodeParam.Gray, mxPngEncodeParam.Palette, mxPngEncodeParam.RGB

    public abstract class mxPngEncodeParam

extends Object

An instance of `ImageEncodeParam` for encoding images in the PNG format.

This class is not a committed part of the JAI API. It may be removed or changed in future releases of JAI.

Nested Class Summary
`static class` | `mxPngEncodeParam.Gray`
`static class` | `mxPngEncodeParam.Palette`
`static class` | `mxPngEncodeParam.RGB`

Field Summary
`protected int` | `bitDepth`
`protected boolean` | `bitDepthSet`
`static int` | `INTENT_ABSOLUTE` Constant for use with the sRGB chunk.
`static int` | `INTENT_PERCEPTUAL` Constant for use with the sRGB chunk.
`static int` | `INTENT_RELATIVE` Constant for use with the sRGB chunk.
`static int` | `INTENT_SATURATION` Constant for use with the sRGB chunk.
`static int` | `PNG_FILTER_AVERAGE` Constant for use in filtering.
`static int` | `PNG_FILTER_NONE` Constant for use in filtering.
`static int` | `PNG_FILTER_PAETH` Constant for use in filtering.
`static int` | `PNG_FILTER_SUB` Constant for use in filtering.
`static int` | `PNG_FILTER_UP` Constant for use in filtering.

Constructor Summary
`mxPngEncodeParam()`

Method Summary
`void` | `addPrivateChunk(String type, byte[] data)` Adds a private chunk, in binary form, to the list of chunks to be stored with this image.
`int` | `filterRow(byte[] currRow, byte[] prevRow, byte[][] scratchRows, int bytesPerRow, int bytesPerPixel)` Performs filtering on a row of an image.
`int` | `getBitDepth()` Returns the desired bit depth for a grayscale image.
`float[]` | `getChromaticity()` Returns the white point and primary chromaticities in CIE (x, y) space.
`String[]` | `getCompressedText()` Returns the text strings to be stored in compressed form with this image as an array of `String`s.
`static mxPngEncodeParam` | `getDefaultEncodeParam(RenderedImage im)` Returns an instance of `PNGEncodeParam.Palette`, `PNGEncodeParam.Gray`, or `PNGEncodeParam.RGB` appropriate for encoding the given image.
`float` | `getGamma()` Returns the file gamma value for the image.
`byte[]` | `getICCProfileData()` Returns the ICC profile data to be stored with this image.
`boolean` | `getInterlacing()` Returns `true` if Adam7 interlacing will be used.
`Date` | `getModificationTime()` Returns the modification time to be stored with this image.
`int` | `getNumPrivateChunks()` Returns the number of private chunks to be written to the output file.
`int[]` | `getPaletteHistogram()` Returns the palette histogram to be stored with this image.
`int[]` | `getPhysicalDimension()` Returns the physical dimension information to be stored with this image.
`byte[]` | `getPrivateChunkData(int index)` Returns the data associated of the private chunk at a given index, as an array of `byte`s.
`String` | `getPrivateChunkType(int index)` Returns the type of the private chunk at a given index, as a 4-character `String`.
`int[]` | `getSignificantBits()` Returns the number of significant bits for each band of the image.
`int` | `getSRGBIntent()` Returns the sRGB rendering intent to be stored with this image.
`String[]` | `getText()` Returns the text strings to be stored in uncompressed form with this image as an array of `String`s.
`boolean` | `isBackgroundSet()` Returns true if a 'bKGD' chunk will be output.
`boolean` | `isChromaticitySet()` Returns true if a 'cHRM' chunk will be output.
`boolean` | `isCompressedTextSet()` Returns true if a 'zTXT' chunk will be output.
`boolean` | `isGammaSet()` Returns true if a 'gAMA' chunk will be output.
`boolean` | `isICCProfileDataSet()` Returns true if a 'iCCP' chunk will be output.
`boolean` | `isModificationTimeSet()` Returns true if a 'tIME' chunk will be output.
`boolean` | `isPaletteHistogramSet()` Returns true if a 'hIST' chunk will be output.
`boolean` | `isPhysicalDimensionSet()` Returns true if a 'pHYS' chunk will be output.
`boolean` | `isSignificantBitsSet()` Returns true if an 'sBIT' chunk will be output.
`boolean` | `isSRGBIntentSet()` Returns true if an 'sRGB' chunk will be output.
`boolean` | `isSuggestedPaletteSet()` Returns true if a 'sPLT' chunk will be output.
`boolean` | `isTextSet()` Returns true if a 'tEXt' chunk will be output.
`boolean` | `isTransparencySet()` Returns true if a 'tRNS' chunk will be output.
`static int` | `paethPredictor(int a, int b, int c)` The Paeth predictor routine used in PNG encoding.
`void` | `removeAllPrivateChunks()` Remove all private chunks associated with this parameter instance.
`void` | `removeUnsafeToCopyPrivateChunks()` Remove all private chunks associated with this parameter instance whose 'safe-to-copy' bit is not set.
`abstract void` | `setBitDepth(int bitDepth)` Sets the desired bit depth of an image.
`void` | `setChromaticity(float[] chromaticity)` Sets the white point and primary chromaticities in CIE (x, y) space.
`void` | `setChromaticity(float whitePointX, float whitePointY, float redX, float redY, float greenX, float greenY, float blueX, float blueY)` A convenience method that calls the array version.
`void` | `setCompressedText(String[] text)` Sets the text strings to be stored in compressed form with this image.
`void` | `setGamma(float gamma)` Sets the file gamma value for the image.
`void` | `setICCProfileData(byte[] ICCProfileData)` Sets the ICC profile data to be stored with this image.
`void` | `setInterlacing(boolean useInterlacing)` Turns Adam7 interlacing on or off.
`void` | `setModificationTime(Date modificationTime)` Sets the modification time, as a `Date`, to be stored with this image.
`void` | `setPaletteHistogram(int[] paletteHistogram)` Sets the palette histogram to be stored with this image.
`void` | `setPhysicalDimension(int[] physicalDimension)` Sets the physical dimension information to be stored with this image.
`void` | `setPhysicalDimension(int xPixelsPerUnit, int yPixelsPerUnit, int unitSpecifier)` A convenience method that calls the array version.
`void` | `setSignificantBits(int[] significantBits)` Sets the number of significant bits for each band of the image.
`void` | `setSRGBIntent(int SRGBIntent)` Sets the sRGB rendering intent to be stored with this image.
`void` | `setSuggestedPalette(mxPngSuggestedPaletteEntry[] palette)` Sets the suggested palette information to be stored with this image.
`void` | `setText(String[] text)` Sets the textual data to be stored in uncompressed form with this image.
`void` | `unsetBackground()` Suppresses the 'bKGD' chunk from being output.
`void` | `unsetBitDepth()` Suppresses the setting of the bit depth of a grayscale image.
`void` | `unsetChromaticity()` Suppresses the 'cHRM' chunk from being output.
`void` | `unsetCompressedText()` Suppresses the 'zTXt' chunk from being output.
`void` | `unsetGamma()` Suppresses the 'gAMA' chunk from being output.
`void` | `unsetICCProfileData()` Suppresses the 'iCCP' chunk from being output.
`void` | `unsetModificationTime()` Suppresses the 'tIME' chunk from being output.
`void` | `unsetPaletteHistogram()` Suppresses the 'hIST' chunk from being output.
`void` | `unsetPhysicalDimension()` Suppresses the 'pHYS' chunk from being output.
`void` | `unsetSignificantBits()` Suppresses the 'sBIT' chunk from being output.
`void` | `unsetSRGBIntent()` Suppresses the 'sRGB' chunk from being output.
`void` | `unsetSuggestedPalette()` Suppresses the 'sPLT' chunk from being output.
`void` | `unsetText()` Suppresses the 'tEXt' chunk from being output.
`void` | `unsetTransparency()` Suppresses the 'tRNS' chunk from being output.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### INTENT_PERCEPTUAL

    public static final int INTENT_PERCEPTUAL

  Constant for use with the sRGB chunk.

  See Also:
    Constant Field Values

### INTENT_RELATIVE

    public static final int INTENT_RELATIVE

  Constant for use with the sRGB chunk.

  See Also:
    Constant Field Values

### INTENT_SATURATION

    public static final int INTENT_SATURATION

  Constant for use with the sRGB chunk.

  See Also:
    Constant Field Values

### INTENT_ABSOLUTE

    public static final int INTENT_ABSOLUTE

  Constant for use with the sRGB chunk.

  See Also:
    Constant Field Values

### PNG_FILTER_NONE

    public static final int PNG_FILTER_NONE

  Constant for use in filtering.

  See Also:
    Constant Field Values

### PNG_FILTER_SUB

    public static final int PNG_FILTER_SUB

  Constant for use in filtering.

  See Also:
    Constant Field Values

### PNG_FILTER_UP

    public static final int PNG_FILTER_UP

  Constant for use in filtering.

  See Also:
    Constant Field Values

### PNG_FILTER_AVERAGE

    public static final int PNG_FILTER_AVERAGE

  Constant for use in filtering.

  See Also:
    Constant Field Values

### PNG_FILTER_PAETH

    public static final int PNG_FILTER_PAETH

  Constant for use in filtering.

  See Also:
    Constant Field Values

### bitDepth

    protected int bitDepth

### bitDepthSet

    protected boolean bitDepthSet

Constructor Detail

### mxPngEncodeParam

    public mxPngEncodeParam()

Method Detail

### getDefaultEncodeParam

    public static mxPngEncodeParam getDefaultEncodeParam(RenderedImage im)

  Returns an instance of `PNGEncodeParam.Palette`, `PNGEncodeParam.Gray`, or `PNGEncodeParam.RGB` appropriate for encoding the given image.

  If the image has an `IndexColorModel`, an instance of `PNGEncodeParam.Palette` is returned. Otherwise, if the image has 1 or 2 bands an instance of `PNGEncodeParam.Gray` is returned. In all other cases an instance of `PNGEncodeParam.RGB` is returned.

  Note that this method does not provide any guarantee that the given image will be successfully encoded by the PNG encoder, as it only performs a very superficial analysis of the image structure.

### setBitDepth

    public abstract void setBitDepth(int bitDepth)

  Sets the desired bit depth of an image.

### getBitDepth

    public int getBitDepth()

  Returns the desired bit depth for a grayscale image.

  If the bit depth has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the bit depth is not set.

### unsetBitDepth

    public void unsetBitDepth()

  Suppresses the setting of the bit depth of a grayscale image. The depth of the encoded image will be inferred from the source image bit depth, rounded up to the next power of 2 between 1 and 16.

### setInterlacing

    public void setInterlacing(boolean useInterlacing)

  Turns Adam7 interlacing on or off.

### getInterlacing

    public boolean getInterlacing()

  Returns `true` if Adam7 interlacing will be used.

### unsetBackground

    public void unsetBackground()

  Suppresses the 'bKGD' chunk from being output. For API compatibility with JAI 1.0, the superclass defines this method to throw a `RuntimeException`; accordingly, subclasses must provide their own implementations.

### isBackgroundSet

    public boolean isBackgroundSet()

  Returns true if a 'bKGD' chunk will be output. For API compatibility with JAI 1.0, the superclass defines this method to throw a `RuntimeException`; accordingly, subclasses must provide their own implementations.

### setChromaticity

    public void setChromaticity(float[] chromaticity)

  Sets the white point and primary chromaticities in CIE (x, y) space.

  The `chromaticity` parameter should be a `float` array of length 8 containing the white point X and Y, red X and Y, green X and Y, and blue X and Y values in order.

  The 'cHRM' chunk will encode this information.

### setChromaticity

    public void setChromaticity(float whitePointX,
                                float whitePointY,
                                float redX,
                                float redY,
                                float greenX,
                                float greenY,
                                float blueX,
                                float blueY)

  A convenience method that calls the array version.

### getChromaticity

    public float[] getChromaticity()

  Returns the white point and primary chromaticities in CIE (x, y) space.

  See the documentation for the `setChromaticity` method for the format of the returned data.

  If the chromaticity has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the chromaticity is not set.

### unsetChromaticity

    public void unsetChromaticity()

  Suppresses the 'cHRM' chunk from being output.

### isChromaticitySet

    public boolean isChromaticitySet()

  Returns true if a 'cHRM' chunk will be output.

### setGamma

    public void setGamma(float gamma)

  Sets the file gamma value for the image.

  The 'gAMA' chunk will encode this information.

### getGamma

    public float getGamma()

  Returns the file gamma value for the image.

  If the file gamma has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the gamma is not set.

### unsetGamma

    public void unsetGamma()

  Suppresses the 'gAMA' chunk from being output.

### isGammaSet

    public boolean isGammaSet()

  Returns true if a 'gAMA' chunk will be output.

### setPaletteHistogram

    public void setPaletteHistogram(int[] paletteHistogram)

  Sets the palette histogram to be stored with this image. The histogram consists of an array of integers, one per palette entry.

  The 'hIST' chunk will encode this information.

### getPaletteHistogram

    public int[] getPaletteHistogram()

  Returns the palette histogram to be stored with this image.

  If the histogram has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the histogram is not set.

### unsetPaletteHistogram

    public void unsetPaletteHistogram()

  Suppresses the 'hIST' chunk from being output.

### isPaletteHistogramSet

    public boolean isPaletteHistogramSet()

  Returns true if a 'hIST' chunk will be output.

### setICCProfileData

    public void setICCProfileData(byte[] ICCProfileData)

  Sets the ICC profile data to be stored with this image. The profile is represented in raw binary form.

  The 'iCCP' chunk will encode this information.

### getICCProfileData

    public byte[] getICCProfileData()

  Returns the ICC profile data to be stored with this image.

  If the ICC profile has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the ICC profile is not set.

### unsetICCProfileData

    public void unsetICCProfileData()

  Suppresses the 'iCCP' chunk from being output.

### isICCProfileDataSet

    public boolean isICCProfileDataSet()

  Returns true if a 'iCCP' chunk will be output.

### setPhysicalDimension

    public void setPhysicalDimension(int[] physicalDimension)

  Sets the physical dimension information to be stored with this image. The physicalDimension parameter should be a 3-entry array containing the number of pixels per unit in the X direction, the number of pixels per unit in the Y direction, and the unit specifier (0 = unknown, 1 = meters).

  The 'pHYS' chunk will encode this information.

### setPhysicalDimension

    public void setPhysicalDimension(int xPixelsPerUnit,
                                     int yPixelsPerUnit,
                                     int unitSpecifier)

  A convenience method that calls the array version.

### getPhysicalDimension

    public int[] getPhysicalDimension()

  Returns the physical dimension information to be stored with this image.

  If the physical dimension information has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the physical dimension information is not set.

### unsetPhysicalDimension

    public void unsetPhysicalDimension()

  Suppresses the 'pHYS' chunk from being output.

### isPhysicalDimensionSet

    public boolean isPhysicalDimensionSet()

  Returns true if a 'pHYS' chunk will be output.

### setSuggestedPalette

    public void setSuggestedPalette(mxPngSuggestedPaletteEntry[] palette)

  Sets the suggested palette information to be stored with this image. The information is passed to this method as an array of `PNGSuggestedPaletteEntry` objects.

  The 'sPLT' chunk will encode this information.

### unsetSuggestedPalette

    public void unsetSuggestedPalette()

  Suppresses the 'sPLT' chunk from being output.

### isSuggestedPaletteSet

    public boolean isSuggestedPaletteSet()

  Returns true if a 'sPLT' chunk will be output.

### setSignificantBits

    public void setSignificantBits(int[] significantBits)

  Sets the number of significant bits for each band of the image.

  The number of entries in the `significantBits` array must be equal to the number of output bands in the image: 1 for a gray image, 2 for gray+alpha, 3 for index or truecolor, and 4 for truecolor+alpha.

  The 'sBIT' chunk will encode this information.

### getSignificantBits

    public int[] getSignificantBits()

  Returns the number of significant bits for each band of the image.

  If the significant bits values have not previously been set, or have been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the significant bits values are not set.

### unsetSignificantBits

    public void unsetSignificantBits()

  Suppresses the 'sBIT' chunk from being output.

### isSignificantBitsSet

    public boolean isSignificantBitsSet()

  Returns true if an 'sBIT' chunk will be output.

### setSRGBIntent

    public void setSRGBIntent(int SRGBIntent)

  Sets the sRGB rendering intent to be stored with this image. The legal values are 0 = Perceptual, 1 = Relative Colorimetric, 2 = Saturation, and 3 = Absolute Colorimetric. Refer to the PNG specification for information on these values.

  The 'sRGB' chunk will encode this information.

### getSRGBIntent

    public int getSRGBIntent()

  Returns the sRGB rendering intent to be stored with this image.

  If the sRGB intent has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the sRGB intent is not set.

### unsetSRGBIntent

    public void unsetSRGBIntent()

  Suppresses the 'sRGB' chunk from being output.

### isSRGBIntentSet

    public boolean isSRGBIntentSet()

  Returns true if an 'sRGB' chunk will be output.

### setText

    public void setText(String[] text)

  Sets the textual data to be stored in uncompressed form with this image. The data is passed to this method as an array of `String`s.

  The 'tEXt' chunk will encode this information.

### getText

    public String[] getText()

  Returns the text strings to be stored in uncompressed form with this image as an array of `String`s.

  If the text strings have not previously been set, or have been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the text strings are not set.

### unsetText

    public void unsetText()

  Suppresses the 'tEXt' chunk from being output.

### isTextSet

    public boolean isTextSet()

  Returns true if a 'tEXt' chunk will be output.

### setModificationTime

    public void setModificationTime(Date modificationTime)

  Sets the modification time, as a `Date`, to be stored with this image. The internal storage format will use UTC regardless of how the `modificationTime` parameter was created.

  The 'tIME' chunk will encode this information.

### getModificationTime

    public Date getModificationTime()

  Returns the modification time to be stored with this image.

  If the bit depth has not previously been set, or has been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the bit depth is not set.

### unsetModificationTime

    public void unsetModificationTime()

  Suppresses the 'tIME' chunk from being output.

### isModificationTimeSet

    public boolean isModificationTimeSet()

  Returns true if a 'tIME' chunk will be output.

### unsetTransparency

    public void unsetTransparency()

  Suppresses the 'tRNS' chunk from being output.

### isTransparencySet

    public boolean isTransparencySet()

  Returns true if a 'tRNS' chunk will be output.

### setCompressedText

    public void setCompressedText(String[] text)

  Sets the text strings to be stored in compressed form with this image. The data is passed to this method as an array of `String`s.

  The 'zTXt' chunk will encode this information.

### getCompressedText

    public String[] getCompressedText()

  Returns the text strings to be stored in compressed form with this image as an array of `String`s.

  If the compressed text strings have not previously been set, or have been unset, an `IllegalStateException` will be thrown.

  Throws:
    `IllegalStateException` - if the compressed text strings are not set.

### unsetCompressedText

    public void unsetCompressedText()

  Suppresses the 'zTXt' chunk from being output.

### isCompressedTextSet

    public boolean isCompressedTextSet()

  Returns true if a 'zTXT' chunk will be output.

### addPrivateChunk

    public void addPrivateChunk(String type,
                                byte[] data)

  Adds a private chunk, in binary form, to the list of chunks to be stored with this image.

  Parameters:
    `type` - a 4-character String giving the chunk type name.
    `data` - an array of `byte`s containing the chunk data.

### getNumPrivateChunks

    public int getNumPrivateChunks()

  Returns the number of private chunks to be written to the output file.

### getPrivateChunkType

    public String getPrivateChunkType(int index)

  Returns the type of the private chunk at a given index, as a 4-character `String`. The index must be smaller than the return value of `getNumPrivateChunks`.

### getPrivateChunkData

    public byte[] getPrivateChunkData(int index)

  Returns the data associated of the private chunk at a given index, as an array of `byte`s. The index must be smaller than the return value of `getNumPrivateChunks`.

### removeUnsafeToCopyPrivateChunks

    public void removeUnsafeToCopyPrivateChunks()

  Remove all private chunks associated with this parameter instance whose 'safe-to-copy' bit is not set. This may be advisable when transcoding PNG images.

### removeAllPrivateChunks

    public void removeAllPrivateChunks()

  Remove all private chunks associated with this parameter instance.

### paethPredictor

    public static final int paethPredictor(int a,
                                           int b,
                                           int c)

  The Paeth predictor routine used in PNG encoding. This routine is included as a convenience to subclasses that override the `filterRow` method.

### filterRow

    public int filterRow(byte[] currRow,
                         byte[] prevRow,
                         byte[][] scratchRows,
                         int bytesPerRow,
                         int bytesPerPixel)

  Performs filtering on a row of an image. This method may be overridden in order to provide a custom algorithm for choosing the filter type for a given row.

  The method is supplied with the current and previous rows of the image. For the first row of the image, or of an interlacing pass, the previous row array will be filled with zeros as required by the PNG specification.

  The method is also supplied with five scratch arrays. These arrays may be used within the method for any purpose. At method exit, the array at the index given by the return value of the method should contain the filtered data. The return value will also be used as the filter type.

  The default implementation of the method performs a trial encoding with each of the filter types, and computes the sum of absolute values of the differences between the raw bytes of the current row and the predicted values. The index of the filter producing the smallest result is returned.

  As an example, to perform only 'sub' filtering, this method could be implemented (non-optimally) as follows:

       for (int i = bytesPerPixel; i < bytesPerRow + bytesPerPixel; i++) {
           int curr = currRow[i] & 0xff;
           int left = currRow[i - bytesPerPixel] & 0xff;
           scratchRow[PNG_FILTER_SUB][i] = (byte)(curr - left);
       }
       return PNG_FILTER_SUB;

  Parameters:
    `currRow` - The current row as an array of `byte`s of length at least `bytesPerRow + bytesPerPixel`. The pixel data starts at index `bytesPerPixel`; the initial `bytesPerPixel` bytes are zero.
    `prevRow` - The current row as an array of `byte`s The pixel data starts at index `bytesPerPixel`; the initial `bytesPerPixel` bytes are zero.
    `scratchRows` - An array of 5 `byte` arrays of length at least `bytesPerRow + bytesPerPixel`, useable to hold temporary results. The filtered row will be returned as one of the entries of this array. The returned filtered data should start at index `bytesPerPixel`; The initial `bytesPerPixel` bytes are not used.
    `bytesPerRow` - The number of bytes in the image row. This value will always be greater than 0.
    `bytesPerPixel` - The number of bytes representing a single pixel, rounded up to an integer. This is the 'bpp' parameter described in the PNG specification.
  Returns:
    The filter type to be used. The entry of `scratchRows[]` at this index holds the filtered data.

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Copyright (c) 2010 Gaudenz Alder. All rights reserved.