pngimagewriter.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

            cs.writeInt(metadata.cHRM_whitePointY); 
            cs.writeInt(metadata.cHRM_redX);
            cs.writeInt(metadata.cHRM_redY);
            cs.writeInt(metadata.cHRM_greenX);
            cs.writeInt(metadata.cHRM_greenY);
            cs.writeInt(metadata.cHRM_blueX);
            cs.writeInt(metadata.cHRM_blueY);
            cs.finish();
        }
    }

    private void write_gAMA() throws IOException {
        if (metadata.gAMA_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.gAMA_TYPE, stream);
            cs.writeInt(metadata.gAMA_gamma);
            cs.finish();
        }
    }

    private void write_iCCP() throws IOException {
        if (metadata.iCCP_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.iCCP_TYPE, stream);
            cs.writeBytes(metadata.iCCP_profileName);
            cs.writeByte(0); // null terminator

            cs.writeByte(metadata.iCCP_compressionMethod);
            cs.write(metadata.iCCP_compressedProfile);
            cs.finish();
        }
    }

    private void write_sBIT() throws IOException {
        if (metadata.sBIT_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.sBIT_TYPE, stream);
            int colorType = metadata.IHDR_colorType;
            if (metadata.sBIT_colorType != colorType) {
                processWarningOccurred(0,
"sBIT metadata has wrong color type.\n" +
"The chunk will not be written.");
                return;
            }

            if (colorType == PNGImageReader.PNG_COLOR_GRAY ||
                colorType == PNGImageReader.PNG_COLOR_GRAY_ALPHA) {
                cs.writeByte(metadata.sBIT_grayBits);
            } else if (colorType == PNGImageReader.PNG_COLOR_RGB ||
                       colorType == PNGImageReader.PNG_COLOR_PALETTE ||
                       colorType == PNGImageReader.PNG_COLOR_RGB_ALPHA) {
                cs.writeByte(metadata.sBIT_redBits);
                cs.writeByte(metadata.sBIT_greenBits);
                cs.writeByte(metadata.sBIT_blueBits);
            }

            if (colorType == PNGImageReader.PNG_COLOR_GRAY_ALPHA ||
                colorType == PNGImageReader.PNG_COLOR_RGB_ALPHA) {
                cs.writeByte(metadata.sBIT_alphaBits);
            }
            cs.finish();
        }
    }

    private void write_sRGB() throws IOException {
        if (metadata.sRGB_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.sRGB_TYPE, stream);
            cs.writeByte(metadata.sRGB_renderingIntent);
            cs.finish();
        }
    }

    private void write_PLTE() throws IOException {
        if (metadata.PLTE_present) {
            if (metadata.IHDR_colorType == PNGImageReader.PNG_COLOR_GRAY ||
              metadata.IHDR_colorType == PNGImageReader.PNG_COLOR_GRAY_ALPHA) {
                // PLTE cannot occur in a gray image

                processWarningOccurred(0,
"A PLTE chunk may not appear in a gray or gray alpha image.\n" +
"The chunk will not be written");
                return;
            }

            ChunkStream cs = new ChunkStream(PNGImageReader.PLTE_TYPE, stream);

            int numEntries = metadata.PLTE_red.length;
            byte[] palette = new byte[numEntries*3];
            int index = 0;
            for (int i = 0; i < numEntries; i++) {
                palette[index++] = metadata.PLTE_red[i];
                palette[index++] = metadata.PLTE_green[i];
                palette[index++] = metadata.PLTE_blue[i];
            }

            cs.write(palette);
            cs.finish();
        }
    }

    private void write_hIST() throws IOException, IIOException {
        if (metadata.hIST_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.hIST_TYPE, stream);

            if (!metadata.PLTE_present) {
                throw new IIOException("hIST chunk without PLTE chunk!");
            }
            
            cs.writeChars(metadata.hIST_histogram,
                          0, metadata.hIST_histogram.length);
            cs.finish();
        }
    }

    private void write_tRNS() throws IOException, IIOException {
        if (metadata.tRNS_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.tRNS_TYPE, stream);
            int colorType = metadata.IHDR_colorType;
            int chunkType = metadata.tRNS_colorType;

            // Special case: image is RGB and chunk is Gray
            // Promote chunk contents to RGB
            int chunkRed = metadata.tRNS_red;
            int chunkGreen = metadata.tRNS_green;
            int chunkBlue = metadata.tRNS_blue;
            if (colorType == PNGImageReader.PNG_COLOR_RGB &&
                chunkType == PNGImageReader.PNG_COLOR_GRAY) {
                chunkType = colorType;
                chunkRed = chunkGreen = chunkBlue = 
                    metadata.tRNS_gray;
            }

            if (chunkType != colorType) {
                processWarningOccurred(0,
"tRNS metadata has incompatible color type.\n" +
"The chunk will not be written.");
                return;
            }

            if (colorType == PNGImageReader.PNG_COLOR_PALETTE) {
                if (!metadata.PLTE_present) {
                    throw new IIOException("tRNS chunk without PLTE chunk!");
                }
                cs.write(metadata.tRNS_alpha);
            } else if (colorType == PNGImageReader.PNG_COLOR_GRAY) {
                cs.writeShort(metadata.tRNS_gray);
            } else if (colorType == PNGImageReader.PNG_COLOR_RGB) {
                cs.writeShort(chunkRed);
                cs.writeShort(chunkGreen);
                cs.writeShort(chunkBlue);
            } else {
                throw new IIOException("tRNS chunk for color type 4 or 6!");
            }
            cs.finish();
        }
    }

    private void write_bKGD() throws IOException {
        if (metadata.bKGD_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.bKGD_TYPE, stream);
            int colorType = metadata.IHDR_colorType & 0x3;
            int chunkType = metadata.bKGD_colorType;

            // Special case: image is RGB(A) and chunk is Gray
            // Promote chunk contents to RGB
            int chunkRed = metadata.bKGD_red;
            int chunkGreen = metadata.bKGD_red;
            int chunkBlue = metadata.bKGD_red;
            if (colorType == PNGImageReader.PNG_COLOR_RGB &&
                chunkType == PNGImageReader.PNG_COLOR_GRAY) {
                // Make a gray bKGD chunk look like RGB
                chunkType = colorType;
                chunkRed = chunkGreen = chunkBlue = 
                    metadata.bKGD_gray;
            }

            // Ignore status of alpha in colorType 
            if (chunkType != colorType) {
                processWarningOccurred(0,
"bKGD metadata has incompatible color type.\n" +
"The chunk will not be written.");
                return;
            }

            if (colorType == PNGImageReader.PNG_COLOR_PALETTE) {
                cs.writeByte(metadata.bKGD_index);
            } else if (colorType == PNGImageReader.PNG_COLOR_GRAY ||
                       colorType == PNGImageReader.PNG_COLOR_GRAY_ALPHA) {
                cs.writeShort(metadata.bKGD_gray);
            } else { // colorType == PNGImageReader.PNG_COLOR_RGB ||
                     // colorType == PNGImageReader.PNG_COLOR_RGB_ALPHA
                cs.writeShort(chunkRed);
                cs.writeShort(chunkGreen);
                cs.writeShort(chunkBlue);
            }
            cs.finish();
        }
    }

    private void write_pHYs() throws IOException {
        if (metadata.pHYs_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.pHYs_TYPE, stream);
            cs.writeInt(metadata.pHYs_pixelsPerUnitXAxis);
            cs.writeInt(metadata.pHYs_pixelsPerUnitYAxis);
            cs.writeByte(metadata.pHYs_unitSpecifier);
            cs.finish();
        }
    }

    private void write_sPLT() throws IOException {
        if (metadata.sPLT_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.sPLT_TYPE, stream);

            cs.writeBytes(metadata.sPLT_paletteName);
            cs.writeByte(0); // null terminator

            cs.writeByte(metadata.sPLT_sampleDepth);
            int numEntries = metadata.sPLT_red.length;

            if (metadata.sPLT_sampleDepth == 8) {
                for (int i = 0; i < numEntries; i++) {
                    cs.writeByte(metadata.sPLT_red[i]);
                    cs.writeByte(metadata.sPLT_green[i]);
                    cs.writeByte(metadata.sPLT_blue[i]);
                    cs.writeByte(metadata.sPLT_alpha[i]);
                    cs.writeShort(metadata.sPLT_frequency[i]);
                }
            } else { // sampleDepth == 16
                for (int i = 0; i < numEntries; i++) {
                    cs.writeShort(metadata.sPLT_red[i]);
                    cs.writeShort(metadata.sPLT_green[i]);
                    cs.writeShort(metadata.sPLT_blue[i]);
                    cs.writeShort(metadata.sPLT_alpha[i]);
                    cs.writeShort(metadata.sPLT_frequency[i]);
                }
            }
            cs.finish();
        }
    }

    private void write_tIME() throws IOException {
        if (metadata.tIME_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.tIME_TYPE, stream);
            cs.writeShort(metadata.tIME_year);
            cs.writeByte(metadata.tIME_month);
            cs.writeByte(metadata.tIME_day);
            cs.writeByte(metadata.tIME_hour);
            cs.writeByte(metadata.tIME_minute);
            cs.writeByte(metadata.tIME_second);
            cs.finish();
        }
    }

    private void write_tEXt() throws IOException {
        Iterator keywordIter = metadata.tEXt_keyword.iterator();
        Iterator textIter = metadata.tEXt_text.iterator();

        while (keywordIter.hasNext()) {
            ChunkStream cs = new ChunkStream(PNGImageReader.tEXt_TYPE, stream);
            String keyword = (String)keywordIter.next();
            cs.writeBytes(keyword);
            cs.writeByte(0);

            String text = (String)textIter.next();
            cs.writeBytes(text);
            cs.finish();
        }
    }

    private byte[] deflate(String s) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        DeflaterOutputStream dos = new DeflaterOutputStream(baos);

        int len = s.length();
        for (int i = 0; i < len; i++) {
            dos.write((int)s.charAt(i));
        }
        dos.close();
        
        return baos.toByteArray();
    }

    private void write_iTXt() throws IOException {
        Iterator keywordIter = metadata.iTXt_keyword.iterator();
        Iterator flagIter = metadata.iTXt_compressionFlag.iterator();
        Iterator methodIter = metadata.iTXt_compressionMethod.iterator();
        Iterator languageIter = metadata.iTXt_languageTag.iterator();
        Iterator translatedKeywordIter =
            metadata.iTXt_translatedKeyword.iterator();
        Iterator textIter = metadata.iTXt_text.iterator();

        while (keywordIter.hasNext()) {
            ChunkStream cs = new ChunkStream(PNGImageReader.iTXt_TYPE, stream);
            String keyword = (String)keywordIter.next();
            cs.writeBytes(keyword);
            cs.writeByte(0);

            int flag = ((Integer)flagIter.next()).intValue();
            cs.writeByte(flag);
            int method = ((Integer)methodIter.next()).intValue();
            cs.writeByte(method);

            String languageTag = (String)languageIter.next();
            cs.writeBytes(languageTag);
            cs.writeByte(0);

            String translatedKeyword = (String)translatedKeywordIter.next();
            cs.writeBytes(translatedKeyword);
            cs.writeByte(0);

            String text = (String)textIter.next();
            if (flag == 1) {
                cs.write(deflate(text));
            } else {
                cs.writeUTF(text);
            }
            cs.finish();
        }
    }

    private void write_zTXt() throws IOException {
        Iterator keywordIter = metadata.zTXt_keyword.iterator();
        Iterator methodIter = metadata.zTXt_compressionMethod.iterator();
        Iterator textIter = metadata.zTXt_text.iterator();

        while (keywordIter.hasNext()) {
            ChunkStream cs = new ChunkStream(PNGImageReader.zTXt_TYPE, stream);
            String keyword = (String)keywordIter.next();
            cs.writeBytes(keyword);
            cs.writeByte(0);

            int compressionMethod = ((Integer)methodIter.next()).intValue();
            cs.writeByte(compressionMethod);

            String text = (String)textIter.next();
            cs.write(deflate(text));
            cs.finish();
        }
    }

    private void writeUnknownChunks() throws IOException {
        Iterator typeIter = metadata.unknownChunkType.iterator();
        Iterator dataIter = metadata.unknownChunkData.iterator();

        while (typeIter.hasNext() && dataIter.hasNext()) {
            String type = (String)typeIter.next();
            ChunkStream cs = new ChunkStream(chunkType(type), stream);
            byte[] data = (byte[])dataIter.next();
            cs.write(data);
            cs.finish();
        }
    }

    private static int chunkType(String typeString) {
        char c0 = typeString.charAt(0);
        char c1 = typeString.charAt(1);
        char c2 = typeString.charAt(2);
        char c3 = typeString.charAt(3);

        int type = (c0 << 24) | (c1 << 16) | (c2 << 8) | c3;
        return type;
    }

    private void encodePass(ImageOutputStream os,
                            RenderedImage image,
                            int xOffset, int yOffset,
                            int xSkip, int ySkip) throws IOException {
        int minX = sourceXOffset;
        int minY = sourceYOffset;
        int width = sourceWidth;
        int height = sourceHeight;
        
        // Adjust offsets and skips based on source subsampling factors
        xOffset *= periodX;
        xSkip *= periodX;
        yOffset *= periodY;
        ySkip *= periodY;

        // Early exit if no data for this pass
        int hpixels = (width - xOffset + xSkip - 1)/xSkip;
        int vpixels = (height - yOffset + ySkip - 1)/ySkip;
        if (hpixels == 0 || vpixels == 0) {
            return;
        }

        // Convert X offset and skip from pixels to samples
        xOffset *= numBands;
        xSkip *= numBands;