java – SWT：如何进行高质量图像调整大小

我的应用程序需要调整 ImageData的大小.不幸的是,我没有得到我想要的GC结果(带有抗锯齿和高插值)或ImageData.scaledTo().得到的图像质量太低而无法接受.什么是高质量ImageData调整大小的最佳方法？

编辑：我缩小了.

解决方法

AWT提供不同模式的图像缩放.对于缩小尺寸,Area Averaging提供最佳质量.当然,人们可以重新实现SWT的区域平均缩放算法,或者,对于通常足够的快速解决方案：

>将SWT图像转换为AWT图像
>使用适当的模式重新缩放它(如果缩小则平均区域,否则为双线性)
>将其转换回SWT图像

可以在here找到在SWT和AWT图像之间进行转换的代码.

/**
 * Resizes an image,using the given scaling factor. Constructs a new image resource,please take care of resource
 * disposal if you no longer need the original one. This method is optimized for quality,not for speed.
 * 
 * @param image source image
 * @param scale scale factor (<1 = downscaling,>1 = upscaling)
 * @return scaled image
 */
public static org.eclipse.swt.graphics.Image resize (org.eclipse.swt.graphics.Image image,float scale) {
    int w = image.getBounds().width;
    int h = image.getBounds().height;

    // convert to buffered image
    BufferedImage img = convertToAWT(image.getimageData());

    // resize buffered image
    int newWidth = Math.round(scale * w);
    int newHeight = Math.round(scale * h);

    // determine scaling mode for best result: if downsizing,use area averaging,if upsizing,use smooth scaling
    // (usually bilinear).
    int mode = scale < 1 ? BufferedImage.SCALE_AREA_AVERAGING : BufferedImage.SCALE_SMOOTH;
    java.awt.Image scaledImage = img.getScaledInstance(newWidth,newHeight,mode);

    // convert the scaled image back to a buffered image
    img = new BufferedImage(newWidth,BufferedImage.TYPE_INT_RGB);
    img.getGraphics().drawImage(scaledImage,null);

    // reconstruct swt image
    ImageData imageData = convertToSWT(img);
    return new org.eclipse.swt.graphics.Image(display.getDefault(),imageData);
}

public static BufferedImage convertToAWT (ImageData data) {
    ColorModel colorModel = null;
    PaletteData palette = data.palette;
    if (palette.isDirect) {
        colorModel = new DirectColorModel(data.depth,palette.redMask,palette.greenMask,palette.blueMask);
        BufferedImage bufferedImage = new BufferedImage(colorModel,colorModel.createCompatibleWritableRaster(data.width,data.height),false,null);
        WritableRaster raster = bufferedImage.getRaster();
        int[] pixelArray = new int[3];
        for (int y = 0; y < data.height; y++) {
            for (int x = 0; x < data.width; x++) {
                int pixel = data.getPixel(x,y);
                RGB rgb = palette.getRGB(pixel);
                pixelArray[0] = rgb.red;
                pixelArray[1] = rgb.green;
                pixelArray[2] = rgb.blue;
                raster.setPixels(x,y,1,pixelArray);
            }
        }
        return bufferedImage;
    } else {
        RGB[] rgbs = palette.getRGBs();
        byte[] red = new byte[rgbs.length];
        byte[] green = new byte[rgbs.length];
        byte[] blue = new byte[rgbs.length];
        for (int i = 0; i < rgbs.length; i++) {
            RGB rgb = rgbs[i];
            red[i] = (byte) rgb.red;
            green[i] = (byte) rgb.green;
            blue[i] = (byte) rgb.blue;
        }
        if (data.transparentPixel != -1) {
            colorModel = new IndexColorModel(data.depth,rgbs.length,red,green,blue,data.transparentPixel);
        } else {
            colorModel = new IndexColorModel(data.depth,blue);
        }
        BufferedImage bufferedImage = new BufferedImage(colorModel,null);
        WritableRaster raster = bufferedImage.getRaster();
        int[] pixelArray = new int[1];
        for (int y = 0; y < data.height; y++) {
            for (int x = 0; x < data.width; x++) {
                int pixel = data.getPixel(x,y);
                pixelArray[0] = pixel;
                raster.setPixel(x,pixelArray);
            }
        }
        return bufferedImage;
    }
}

public static ImageData convertToSWT (BufferedImage bufferedImage) {
    if (bufferedImage.getColorModel() instanceof DirectColorModel) {
        DirectColorModel colorModel = (DirectColorModel) bufferedImage.getColorModel();
        PaletteData palette = new PaletteData(colorModel.getRedMask(),colorModel.getGreenMask(),colorModel.getBlueMask());
        ImageData data = new ImageData(bufferedImage.getWidth(),bufferedImage.getHeight(),colorModel.getPixelSize(),palette);
        WritableRaster raster = bufferedImage.getRaster();
        int[] pixelArray = new int[3];
        for (int y = 0; y < data.height; y++) {
            for (int x = 0; x < data.width; x++) {
                raster.getPixel(x,pixelArray);
                int pixel = palette.getPixel(new RGB(pixelArray[0],pixelArray[1],pixelArray[2]));
                data.setPixel(x,pixel);
            }
        }
        return data;
    } else if (bufferedImage.getColorModel() instanceof IndexColorModel) {
        IndexColorModel colorModel = (IndexColorModel) bufferedImage.getColorModel();
        int size = colorModel.getMapSize();
        byte[] reds = new byte[size];
        byte[] greens = new byte[size];
        byte[] blues = new byte[size];
        colorModel.getReds(reds);
        colorModel.getGreens(greens);
        colorModel.getBlues(blues);
        RGB[] rgbs = new RGB[size];
        for (int i = 0; i < rgbs.length; i++) {
            rgbs[i] = new RGB(reds[i] & 0xFF,greens[i] & 0xFF,blues[i] & 0xFF);
        }
        PaletteData palette = new PaletteData(rgbs);
        ImageData data = new ImageData(bufferedImage.getWidth(),palette);
        data.transparentPixel = colorModel.getTransparentPixel();
        WritableRaster raster = bufferedImage.getRaster();
        int[] pixelArray = new int[1];
        for (int y = 0; y < data.height; y++) {
            for (int x = 0; x < data.width; x++) {
                raster.getPixel(x,pixelArray);
                data.setPixel(x,pixelArray[0]);
            }
        }
        return data;
    }
    return null;
}