一、相關概念
1、Drawable就是一個可畫的對象,其可能是一張位圖(BitmapDrawable),也可能是一個圖形(ShapeDrawable),還有可能是一個圖層(LayerDrawable),我們根據畫圖的需求,建立相應的可畫對象
2、Canvas畫布,繪圖的目的區域,用于繪圖
3、Bitmap位圖,用于圖的處理
4、Matrix矩陣
二、Bitmap
1、從資源中擷取Bitmap
1 Resources res = getResources(); 2 Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.icon);
2、Bitmap → byte[]
1 public byte[] Bitmap2Bytes(Bitmap bm) { 2 ByteArrayOutputStream baos = new ByteArrayOutputStream(); 3 bm.compress(Bitmap.CompressFormat.PNG, 100, baos); 4 return baos.toByteArray(); 5 }
3、byte[] → Bitmap
1 public Bitmap Bytes2Bimap(byte[] b) { 2 if (b.length != 0) { 3 return BitmapFactory.decodeByteArray(b, 0, b.length); 4 } else { 5 return null; 6 } 7 }
4、Bitmap縮放
1 public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) { 2 int w = bitmap.getWidth(); 3 int h = bitmap.getHeight(); 4 Matrix matrix = new Matrix(); 5 float scaleWidth = ((float) width / w); 6 float scaleHeight = ((float) height / h); 7 matrix.postScale(scaleWidth, scaleHeight); 8 Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true); 9 return newbmp; 10 }
5、将Drawable轉化為Bitmap
1 public static Bitmap drawableToBitmap(Drawable drawable) { 2 // 取 drawable 的長寬 3 int w = drawable.getIntrinsicWidth(); 4 int h = drawable.getIntrinsicHeight(); 5 6 // 取 drawable 的顔色格式 7 Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 8 : Bitmap.Config.RGB_565; 9 // 建立對應 bitmap 10 Bitmap bitmap = Bitmap.createBitmap(w, h, config); 11 // 建立對應 bitmap 的畫布 12 Canvas canvas = new Canvas(bitmap); 13 drawable.setBounds(0, 0, w, h); 14 // 把 drawable 内容畫到畫布中 15 drawable.draw(canvas); 16 return bitmap; 17 }
6、獲得圓角圖檔
1 public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) { 2 int w = bitmap.getWidth(); 3 int h = bitmap.getHeight(); 4 Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888); 5 Canvas canvas = new Canvas(output); 6 final int color = 0xff424242; 7 final Paint paint = new Paint(); 8 final Rect rect = new Rect(0, 0, w, h); 9 final RectF rectF = new RectF(rect); 10 paint.setAntiAlias(true); 11 canvas.drawARGB(0, 0, 0, 0); 12 paint.setColor(color); 13 canvas.drawRoundRect(rectF, roundPx, roundPx, paint); 14 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 15 canvas.drawBitmap(bitmap, rect, rect, paint); 16 17 return output; 18 }
7、獲得帶倒影的圖檔
1 public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) { 2 final int reflectionGap = 4; 3 int w = bitmap.getWidth(); 4 int h = bitmap.getHeight(); 5 6 Matrix matrix = new Matrix(); 7 matrix.preScale(1, -1); 8 9 Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w, 10 h / 2, matrix, false); 11 12 Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2), 13 Config.ARGB_8888); 14 15 Canvas canvas = new Canvas(bitmapWithReflection); 16 canvas.drawBitmap(bitmap, 0, 0, null); 17 Paint deafalutPaint = new Paint(); 18 canvas.drawRect(0, h, w, h + reflectionGap, deafalutPaint); 19 20 canvas.drawBitmap(reflectionImage, 0, h + reflectionGap, null); 21 22 Paint paint = new Paint(); 23 LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0, 24 bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 25 0x00ffffff, TileMode.CLAMP); 26 paint.setShader(shader); 27 // Set the Transfer mode to be porter duff and destination in 28 paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN)); 29 // Draw a rectangle using the paint with our linear gradient 30 canvas.drawRect(0, h, w, bitmapWithReflection.getHeight() 31 + reflectionGap, paint); 32 33 return bitmapWithReflection; 34 }
三、Drawable
1、Bitmap轉換成Drawable
1 Bitmap bm=xxx; //xxx根據你的情況擷取 2 BitmapDrawable bd= new BitmapDrawable(getResource(), bm); 3 因為BtimapDrawable是Drawable的子類,最終直接使用bd對象即可。
2、Drawable縮放
1 public static Drawable zoomDrawable(Drawable drawable, int w, int h) { 2 int width = drawable.getIntrinsicWidth(); 3 int height = drawable.getIntrinsicHeight(); 4 // drawable轉換成bitmap 5 Bitmap oldbmp = drawableToBitmap(drawable); 6 // 建立操作圖檔用的Matrix對象 7 Matrix matrix = new Matrix(); 8 // 計算縮放比例 9 float sx = ((float) w / width); 10 float sy = ((float) h / height); 11 // 設定縮放比例 12 matrix.postScale(sx, sy); 13 // 建立新的bitmap,其内容是對原bitmap的縮放後的圖 14 Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height, 15 matrix, true); 16 return new BitmapDrawable(newbmp); 17 }