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ImageView 变灰、倒影、圆角、加水印

作者:逆锋起笔
  • 2022 年 3 月 03 日
  • 本文字数:2823 字

    阅读完需:约 9 分钟

ImageView变灰、倒影、圆角、加水印

Android 开发中,一些小经验,如果没有及时总结记录,那么下次遇到了之后,又会同样的搜索思考测试,这就耽误了很多时间,效率不高,ImageView 是特别常用的一个控件,而图片加圆角、加水印、变灰也是特别常见的需求,其实代码就那么固定几行,下面看具体实现。


本文用到的示例原图:



下面就将这张图片处理成各种样式。

将彩色图片转化为灰图


/**  * 将彩色图转换为灰度图  * @param img 位图  * @return 返回转换好的位图  */  public Bitmap convertGreyImg(Bitmap img) {    int width = img.getWidth(); //获取位图的宽    int height = img.getHeight(); //获取位图的高    int []pixels = new int[width * height]; //通过位图的大小创建像素点数组    img.getPixels(pixels, 0, width, 0, 0, width, height);    int alpha = 0xFF << 24;        for(int i = 0; i < height; i++) {      for(int j = 0; j < width; j++) {        int grey = pixels[width * i + j];        int red = ((grey & 0x00FF0000 ) >> 16);        int green = ((grey & 0x0000FF00) >> 8);        int blue = (grey & 0x000000FF);        grey = (int)((float) red * 0.3 + (float)green * 0.59 + (float)blue * 0.11);        grey = alpha | (grey << 16) | (grey << 8) | grey;        pixels[width * i + j] = grey;        }     }   Bitmap result = Bitmap.createBitmap(width, height, Config.RGB_565);   result.setPixels(pixels, 0, width, 0, 0, width, height);      return result; }
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将图片转成圆角图


public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888); Canvas canvas = new Canvas(output);
final int color = 0xff424242; final Paint paint = new Paint(); final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight()); final RectF rectF = new RectF(rect);
paint.setAntiAlias(true); canvas.drawARGB(0, 0, 0, 0); paint.setColor(color); canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); canvas.drawBitmap(bitmap, rect, rect, paint);
return output;}
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图片添加倒影效果


/** * 获得带倒影的图片方法 */public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {    final int reflectionGap = 4;    int width = bitmap.getWidth();    int height = bitmap.getHeight();
Matrix matrix = new Matrix(); matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, height / 2, width, height / 2, matrix, false);
Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height / 2), Config.ARGB_8888);
Canvas canvas = new Canvas(bitmapWithReflection); canvas.drawBitmap(bitmap, 0, 0, null); Paint deafalutPaint = new Paint(); canvas.drawRect(0, height, width, height + reflectionGap, deafalutPaint);
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
Paint paint = new Paint(); LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0, bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP); paint.setShader(shader); // Set the Transfer mode to be porter duff and destination in paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN)); // Draw a rectangle using the paint with our linear gradient canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint); return bitmapWithReflection;}
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添加水印


/** *  * @param src *            要添加水印的图片 * @param 水印 * @return 添加了水印的图片 */private Bitmap createBitmap(Bitmap src, Bitmap watermark) {    String tag = "createBitmap";    Log.d(tag, "create a new bitmap");    if (src == null) {        return null;    }
int w = src.getWidth(); int h = src.getHeight(); int ww = watermark.getWidth(); int wh = watermark.getHeight(); // create the new blank bitmap Bitmap newb = Bitmap.createBitmap(w, h, Config.ARGB_8888);// 创建一个新的和SRC长度宽度一样的位图 Canvas cv = new Canvas(newb); // draw src into cv.drawBitmap(src, 0, 0, null);// 在 0,0坐标开始画入src // draw watermark into cv.drawBitmap(watermark, w - ww + 5, h - wh + 5, null);// 在src的右下角画入水印 // save all clip cv.save(Canvas.ALL_SAVE_FLAG);// 保存 // store cv.restore();// 存储 return newb;}
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生成图片:View 转成 Bitmap

/** * 把一个View的对象转换成bitmap */static Bitmap getViewBitmap(View v) {
v.clearFocus(); v.setPressed(false);
// 能画缓存就返回false boolean willNotCache = v.willNotCacheDrawing(); v.setWillNotCacheDrawing(false); int color = v.getDrawingCacheBackgroundColor(); v.setDrawingCacheBackgroundColor(0); if (color != 0) { v.destroyDrawingCache(); } v.buildDrawingCache(); Bitmap cacheBitmap = v.getDrawingCache(); if (cacheBitmap == null) { Log.e(TAG, "failed getViewBitmap(" + v + ")", new RuntimeException()); return null; } Bitmap bitmap = Bitmap.createBitmap(cacheBitmap); // Restore the view v.destroyDrawingCache(); v.setWillNotCacheDrawing(willNotCache); v.setDrawingCacheBackgroundColor(color); return bitmap;}
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总结

这篇文章总结记录了关于 ImageView 的 5 个变换技巧,可以作为知识库使用,随着工作经验的积累,每个开发者都应该有自己的知识库,方便提高开发效率,总结经验。


我是一名安卓开发工程师,最近正在学习 Java 后端知识,每天保持学习,掌握一项技能其实用不了多长时间,加油!

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ImageView变灰、倒影、圆角、加水印_android_逆锋起笔_InfoQ写作平台