ImageView grayed, reflected, rounded, watermarked

Android In development , Some small experience , If there is no summary record in time , So next time you meet , The same search thinking test , This takes a lot of time , The efficiency is not high ,ImageView Is a particularly commonly used control , The picture is rounded 、 Add watermark 、 Graying is also a particularly common requirement , In fact, the code is so fixed for a few lines , Let's look at the specific implementation .

The sample original used in this article ：

Let's deal with this picture into various styles .

Convert color pictures to gray pictures

/** *  Convert a color image into a grayscale image  * @param img  Bitmap  * @return  Returns the converted bitmap  */  public Bitmap convertGreyImg(Bitmap img) {    int width = img.getWidth(); // Get the width of the bitmap     int height = img.getHeight(); // Gets the height of the bitmap     int []pixels = new int[width * height]; // Create an array of pixels by the size of the bitmap     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; }

Turn the picture into a rounded corner

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;}

Add a reflection effect to the picture

/** *  How to get a picture with reflection  */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;}

Add watermark

/** * * @param src *  Image to add watermark  * @param  watermark  * @return  Watermarked pictures  */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);//  Create a new and SRC Bitmap with the same length and width     Canvas cv = new Canvas(newb);    // draw src into    cv.drawBitmap(src, 0, 0, null);//  stay  0,0 The coordinates begin to draw into src    // draw watermark into    cv.drawBitmap(watermark, w - ww + 5, h - wh + 5, null);//  stay src Draw a watermark in the lower right corner of the     // save all clip    cv.save(Canvas.ALL_SAVE_FLAG);//  preservation     // store    cv.restore();//  Storage         return newb;}

Generate pictures ：View Turn into Bitmap

/** *  Put one View The object of is converted to bitmap */static Bitmap getViewBitmap(View v) {    v.clearFocus();    v.setPressed(false);    //  If you can draw the cache, you will return 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;}

summary

Last one The blog summarizes two unusual layout techniques , This article summarizes and records about ImageView Of 5 Three transformation techniques , It can be used as a knowledge base , With the accumulation of working experience , Every developer should have their own knowledge base , It is convenient to improve development efficiency , To sum up your experience .

I am an Android Development Engineer , I'm studying recently Java Back end knowledge , Keep learning every day , It doesn't take long to master a skill , come on. ！