bitmap 合并图片

把两张bitmap覆盖合成为一张图

    /**
     * 把两个位图覆盖合成为一个位图，以底层位图的长宽为基准
     * @param backBitmap 在底部的位图
     * @param frontBitmap 盖在上面的位图
     * @return
     */
    public static Bitmap mergeBitmap(Bitmap backBitmap, Bitmap frontBitmap) {

        if (backBitmap == null || backBitmap.isRecycled() 
                || frontBitmap == null || frontBitmap.isRecycled()) {
            Log.e(TAG, "backBitmap=" + backBitmap + ";frontBitmap=" + frontBitmap);
            return null;
        }
        Bitmap bitmap = backBitmap.copy(Config.ARGB_8888, true);
        Canvas canvas = new Canvas(bitmap);
        Rect baseRect  = new Rect(0, 0, backBitmap.getWidth(), backBitmap.getHeight());
        Rect frontRect = new Rect(0, 0, frontBitmap.getWidth(), frontBitmap.getHeight());
        canvas.drawBitmap(frontBitmap, frontRect, baseRect, null);
        return bitmap;
    }

    /**
     * 把两个位图覆盖合成为一个位图，左右拼接
     * @param leftBitmap 
     * @param rightBitmap 
     * @param isBaseMax 是否以宽度大的位图为准，true则小图等比拉伸，false则大图等比压缩
     * @return
     */
    public static Bitmap mergeBitmap_LR(Bitmap leftBitmap, Bitmap rightBitmap, boolean isBaseMax) {

        if (leftBitmap == null || leftBitmap.isRecycled() 
                || rightBitmap == null || rightBitmap.isRecycled()) {
            JDLog.logError(TAG, "leftBitmap=" + leftBitmap + ";rightBitmap=" + rightBitmap);
            return null;
        }
        int height = 0; // 拼接后的高度，按照参数取大或取小
        if (isBaseMax) {
            height = leftBitmap.getHeight() > rightBitmap.getHeight() ? leftBitmap.getHeight() : rightBitmap.getHeight();
        } else {
            height = leftBitmap.getHeight() < rightBitmap.getHeight() ? leftBitmap.getHeight() : rightBitmap.getHeight();
        }

        // 缩放之后的bitmap
        Bitmap tempBitmapL = leftBitmap;
        Bitmap tempBitmapR = rightBitmap;

        if (leftBitmap.getHeight() != height) {
            tempBitmapL = Bitmap.createScaledBitmap(leftBitmap, (int)(leftBitmap.getWidth()*1f/leftBitmap.getHeight()*height), height, false);
        } else if (rightBitmap.getHeight() != height) {
            tempBitmapR = Bitmap.createScaledBitmap(rightBitmap, (int)(rightBitmap.getWidth()*1f/rightBitmap.getHeight()*height), height, false);
        }

        // 拼接后的宽度
        int width = tempBitmapL.getWidth() + tempBitmapR.getWidth();

        // 定义输出的bitmap
        Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        // 缩放后两个bitmap需要绘制的参数
        Rect leftRect = new Rect(0, 0, tempBitmapL.getWidth(), tempBitmapL.getHeight());
        Rect rightRect  = new Rect(0, 0, tempBitmapR.getWidth(), tempBitmapR.getHeight());

        // 右边图需要绘制的位置，往右边偏移左边图的宽度，高度是相同的
        Rect rightRectT  = new Rect(tempBitmapL.getWidth(), 0, width, height);

        canvas.drawBitmap(tempBitmapL, leftRect, leftRect, null);
        canvas.drawBitmap(tempBitmapR, rightRect, rightRectT, null);
        return bitmap;
    }


    /**
     * 把两个位图覆盖合成为一个位图，上下拼接
     * @param leftBitmap 
     * @param rightBitmap 
     * @param isBaseMax 是否以高度大的位图为准，true则小图等比拉伸，false则大图等比压缩
     * @return
     */
    public static Bitmap mergeBitmap_TB(Bitmap topBitmap, Bitmap bottomBitmap, boolean isBaseMax) {

        if (topBitmap == null || topBitmap.isRecycled() 
                || bottomBitmap == null || bottomBitmap.isRecycled()) {
            JDLog.logError(TAG, "topBitmap=" + topBitmap + ";bottomBitmap=" + bottomBitmap);
            return null;
        }
        int width = 0;
        if (isBaseMax) {
            width = topBitmap.getWidth() > bottomBitmap.getWidth() ? topBitmap.getWidth() : bottomBitmap.getWidth();
        } else {
            width = topBitmap.getWidth() < bottomBitmap.getWidth() ? topBitmap.getWidth() : bottomBitmap.getWidth();
        }
        Bitmap tempBitmapT = topBitmap;
        Bitmap tempBitmapB = bottomBitmap;

        if (topBitmap.getWidth() != width) {
            tempBitmapT = Bitmap.createScaledBitmap(topBitmap, width, (int)(topBitmap.getHeight()*1f/topBitmap.getWidth()*width), false);
        } else if (bottomBitmap.getWidth() != width) {
            tempBitmapB = Bitmap.createScaledBitmap(bottomBitmap, width, (int)(bottomBitmap.getHeight()*1f/bottomBitmap.getWidth()*width), false);
        }

        int height = tempBitmapT.getHeight() + tempBitmapB.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);

        Rect topRect = new Rect(0, 0, tempBitmapT.getWidth(), tempBitmapT.getHeight());
        Rect bottomRect  = new Rect(0, 0, tempBitmapB.getWidth(), tempBitmapB.getHeight());

        Rect bottomRectT  = new Rect(0, tempBitmapT.getHeight(), width, height);

        canvas.drawBitmap(tempBitmapT, topRect, topRect, null);
        canvas.drawBitmap(tempBitmapB, bottomRect, bottomRectT, null);
        return bitmap;
    }