Codenameone 自动录制代号为1的图像

我需要在代码名1中自动录制图像。 Autocrop图像意味着从该图像中删除边框。下面代码的目的是搜索颜色（或透明度）相同的最大可能边界区域，然后从图像中裁剪该区域

为了更好地理解我写的算法，请考虑下面的图片（注意Topx、Topy、Butox、ButMy是谁）：

这是我的密码。你能帮我弄明白什么地方出了问题并解决它吗？正如日志和屏幕截图所报告的，它没有按预期工作：

Image arrowDownIcon = FontImage.createMaterial(FontImage.MATERIAL_ARROW_DROP_DOWN, "Color-Gray", 30);
Form hi = new Form("Hi World", new FlowLayout(Component.CENTER));
hi.getToolbar().hideToolbar();
hi.getContentPane().setUIID("NoMarginNoPadding");
hi.add(new Label(getAutoCroppedImage(arrowDownIcon), "NoMarginNoPadding"));
hi.show();

CSS

截图：

Image arrowDownIcon = FontImage.createMaterial(FontImage.MATERIAL_ARROW_DROP_DOWN, "Color-Gray", 30);
Form hi = new Form("Hi World", new FlowLayout(Component.CENTER));
hi.getToolbar().hideToolbar();
hi.getContentPane().setUIID("NoMarginNoPadding");
hi.add(new Label(getAutoCroppedImage(arrowDownIcon), "NoMarginNoPadding"));
hi.show();

---

您对基线颜色的期望与图像工作的实际情况不符。对于JPEG来说尤其如此，它可以有多种“白色”颜色，并且需要一个阈值。但在某种程度上，对于无损图像格式（如PNG）也是如此，其中alpha等值的行为可能“异常”，例如，有效的PNG文件可以返回0x00ffffff和0x0（两个像素），并且仍然有效

当绘图应用程序有一些透明的内容时，就会发生这种情况，大多数艺术家无法分辨其中的差别，并且应用程序不会丢弃那些不可见的数据。因此，您需要为alpha添加显式测试，例如：

if ((pixels[y * width + x] == baseColor || (pixels[y * width + x] & 0xff000000) == 0) { 
     ... 
}

给了我正确的提示。然而，我的代码还有另外两个错误：第一个错误是比较应该是

color！=baseColor

而不是

color==baseColor

；第二个是绘制新图像的参数应该是

graphics.drawImage（source，-topx，-topy）而不是我写的那些

在我的用例中，阈值是不必要的，但是对于任何想要实现它们的人，我建议使用代码名One
ColorUtil
API而不是按位比较器来获得alpha、红色、绿色和蓝色，因为该API比按位比较器更具可读性和直观性

这是我的固定方法，我还添加了一个屏幕截图来演示它的工作原理：

    /**
     * Autocrop an image, using as base color the pixel at top left
     *
     * @param source
     * @return
     */
    public static Image getAutoCroppedImage(Image source) {
        if (source == null) {
            throw new IllegalArgumentException("ImageUtilities.getCroppedImage -> null source image");
        }
        if (source instanceof FontImage) {
            source = ((FontImage) source).toImage();
        }

        int[] pixels = source.getRGB(); // array instance containing the ARGB data within this image

        // Get top-left pixel color as "baseline" for cropping (it can be any color or transparent)
        int baseColor = pixels[0];

        int width = source.getWidth();
        int height = source.getHeight();

        int topy = 0;
        int topx = 0;
        int bottomy = height - 1;
        int bottomx = width - 1;

        // Search for topy, iterating the pixels from top to bottom
        for (int y = 0; y < height && topy == 0; y++) {
            for (int x = 0; x < width; x++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    topy = y;
                    break;
                }
            }
        }

        // Search for topx, interating the pixels from left to right
        for (int x = 0; x < width && topx == 0; x++) {
            for (int y = 0; y < height; y++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    topx = x;
                    break;
                }
            }
        }

        // Search for bottomy, iterating from bottom to top
        for (int y = height - 1; y >= 0 && bottomy == height - 1; y--) {
            for (int x = 0; x < width; x++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    bottomy = y;
                    break;
                }
            }
        }

        // Search for bottomx, interating from right to left
        for (int x = width - 1; x >= 0 && bottomx == width - 1; x--) {
            for (int y = 0; y < height; y++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    bottomx = x;
                    break;
                }
            }
        }

        Image destination = Image.createImage((bottomx - topx), (bottomy - topy), 0);

        Log.p("Original width: " + width, Log.DEBUG);
        Log.p("Original height: " + height, Log.DEBUG);
        Log.p("Cropped width: " + destination.getWidth(), Log.DEBUG);
        Log.p("Cropped height: " + destination.getHeight(), Log.DEBUG);
        Log.p("Top-left point cropped image: (" + topx + "," + topy + ")", Log.DEBUG);
        Log.p("Bottom-right point cropped image: (" + bottomx + "," + bottomy + ")", Log.DEBUG);

        Graphics graphics = destination.getGraphics();
        graphics.drawImage(source, -topx, -topy);

        return destination;
    }

/**
*使用左上角的像素作为底色自动拍摄图像
*
*@param源
*@返回
*/
公共静态图像getAutoCroppedImage（图像源）{
if（source==null）{
抛出新的IllegalArgumentException（“ImageUtilities.getCroppedImage->null源图像”）；
}
if（FontImage的源实例）{
source=（（FontImage）source.toImage（）；
}
int[]pixels=source.getRGB（）；//包含此图像中的ARGB数据的数组实例
//获取左上角像素颜色作为裁剪的“基线”（可以是任何颜色或透明）
int baseColor=像素[0]；
int width=source.getWidth（）；
int height=source.getHeight（）；
int-topy=0；
int-topx=0；
int bottomy=高度-1；
int bottomx=宽度-1；
//搜索topy，从上到下迭代像素
对于（int y=0；y=0&&bottomy==height-1；y--）{
对于（int x=0；x=0&&bottomx==width-1；x--）{
对于（int y=0；y

截图：

Image arrowDownIcon = FontImage.createMaterial(FontImage.MATERIAL_ARROW_DROP_DOWN, "Color-Gray", 30);
Form hi = new Form("Hi World", new FlowLayout(Component.CENTER));
hi.getToolbar().hideToolbar();
hi.getContentPane().setUIID("NoMarginNoPadding");
hi.add(new Label(getAutoCroppedImage(arrowDownIcon), "NoMarginNoPadding"));
hi.show();

谢谢你，谢了，你给了我正确的提示。我的代码也有其他错误：我添加了一个新的答案，并完全修复了代码，希望它能对其他人有用。我编辑了我的答案，修复了另一个错误。现在应该没事了。
    /**
     * Autocrop an image, using as base color the pixel at top left
     *
     * @param source
     * @return
     */
    public static Image getAutoCroppedImage(Image source) {
        if (source == null) {
            throw new IllegalArgumentException("ImageUtilities.getCroppedImage -> null source image");
        }
        if (source instanceof FontImage) {
            source = ((FontImage) source).toImage();
        }

        int[] pixels = source.getRGB(); // array instance containing the ARGB data within this image

        // Get top-left pixel color as "baseline" for cropping (it can be any color or transparent)
        int baseColor = pixels[0];

        int width = source.getWidth();
        int height = source.getHeight();

        int topy = 0;
        int topx = 0;
        int bottomy = height - 1;
        int bottomx = width - 1;

        // Search for topy, iterating the pixels from top to bottom
        for (int y = 0; y < height && topy == 0; y++) {
            for (int x = 0; x < width; x++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    topy = y;
                    break;
                }
            }
        }

        // Search for topx, interating the pixels from left to right
        for (int x = 0; x < width && topx == 0; x++) {
            for (int y = 0; y < height; y++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    topx = x;
                    break;
                }
            }
        }

        // Search for bottomy, iterating from bottom to top
        for (int y = height - 1; y >= 0 && bottomy == height - 1; y--) {
            for (int x = 0; x < width; x++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    bottomy = y;
                    break;
                }
            }
        }

        // Search for bottomx, interating from right to left
        for (int x = width - 1; x >= 0 && bottomx == width - 1; x--) {
            for (int y = 0; y < height; y++) {
                int color = pixels[y * width + x];
                int alpha = ColorUtil.alpha(color);
                if (color != baseColor && alpha != 0) {
                    bottomx = x;
                    break;
                }
            }
        }

        Image destination = Image.createImage((bottomx - topx), (bottomy - topy), 0);

        Log.p("Original width: " + width, Log.DEBUG);
        Log.p("Original height: " + height, Log.DEBUG);
        Log.p("Cropped width: " + destination.getWidth(), Log.DEBUG);
        Log.p("Cropped height: " + destination.getHeight(), Log.DEBUG);
        Log.p("Top-left point cropped image: (" + topx + "," + topy + ")", Log.DEBUG);
        Log.p("Bottom-right point cropped image: (" + bottomx + "," + bottomy + ")", Log.DEBUG);

        Graphics graphics = destination.getGraphics();
        graphics.drawImage(source, -topx, -topy);

        return destination;
    }