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，創建相應的可畫對象 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、從資源中獲取Bitmap

Java代碼??

Resources?res?=?getResources();??

Bitmap?bmp?=?BitmapFactory.decodeResource(res,?R.drawable.icon);??

?

2、Bitmap → byte[]

Java代碼??

public?byte[]?Bitmap2Bytes(Bitmap?bm)?{??

????ByteArrayOutputStream?baos?=?new?ByteArrayOutputStream();??

????bm.compress(Bitmap.CompressFormat.PNG,?100,?baos);??

????return?baos.toByteArray();??

}??

?3、byte[] → Bitmap

Java代碼??

public?Bitmap?Bytes2Bimap(byte[]?b)?{??

????if?(b.length?!=?0)?{??

????????return?BitmapFactory.decodeByteArray(b,?0,?b.length);??

????}?else?{??

????????return?null;??

????}??

}??

4、Bitmap縮放

Java代碼??

public?static?Bitmap?zoomBitmap(Bitmap?bitmap,?int?width,?int?height)?{??

????int?w?=?bitmap.getWidth();??

????int?h?=?bitmap.getHeight();??

????Matrix?matrix?=?new?Matrix();??

????float?scaleWidth?=?((float)?width?/?w);??

????float?scaleHeight?=?((float)?height?/?h);??

????matrix.postScale(scaleWidth,?scaleHeight);??

????Bitmap?newbmp?=?Bitmap.createBitmap(bitmap,?0,?0,?w,?h,?matrix,?true);??

????return?newbmp;??

}??

??5、將Drawable轉化為Bitmap

Java代碼??

public?static?Bitmap?drawableToBitmap(Drawable?drawable)?{??

????????//?取?drawable?的長寬??

????????int?w?=?drawable.getIntrinsicWidth();??

????????int?h?=?drawable.getIntrinsicHeight();??

??

????????//?取?drawable?的顏色格式??

????????Bitmap.Config?config?=?drawable.getOpacity()?!=?PixelFormat.OPAQUE???Bitmap.Config.ARGB_8888??

????????????????:?Bitmap.Config.RGB_565;??

????????//?建立對應?bitmap??

????????Bitmap?bitmap?=?Bitmap.createBitmap(w,?h,?config);??

????????//?建立對應?bitmap?的畫布??

????????Canvas?canvas?=?new?Canvas(bitmap);??

????????drawable.setBounds(0,?0,?w,?h);??

????????//?把?drawable?內容畫到畫布中??

????????drawable.draw(canvas);??

????????return?bitmap;??

????}??

6、獲得圓角圖片?

Java代碼??

public?static?Bitmap?getRoundedCornerBitmap(Bitmap?bitmap,?float?roundPx)?{??

????int?w?=?bitmap.getWidth();??

????int?h?=?bitmap.getHeight();??

????Bitmap?output?=?Bitmap.createBitmap(w,?h,?Config.ARGB_8888);??

????Canvas?canvas?=?new?Canvas(output);??

????final?int?color?=?0xff424242;??

????final?Paint?paint?=?new?Paint();??

????final?Rect?rect?=?new?Rect(0,?0,?w,?h);??

????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;??

}??

?7、獲得帶倒影的圖片

Java代碼??

public?static?Bitmap?createReflectionImageWithOrigin(Bitmap?bitmap)?{??

????final?int?reflectionGap?=?4;??

????int?w?=?bitmap.getWidth();??

????int?h?=?bitmap.getHeight();??

??

????Matrix?matrix?=?new?Matrix();??

????matrix.preScale(1,?-1);??

??

????Bitmap?reflectionImage?=?Bitmap.createBitmap(bitmap,?0,?h?/?2,?w,??

????????????h?/?2,?matrix,?false);??

??

????Bitmap?bitmapWithReflection?=?Bitmap.createBitmap(w,?(h?+?h?/?2),??

????????????Config.ARGB_8888);??

??

????Canvas?canvas?=?new?Canvas(bitmapWithReflection);??

????canvas.drawBitmap(bitmap,?0,?0,?null);??

????Paint?deafalutPaint?=?new?Paint();??

????canvas.drawRect(0,?h,?w,?h?+?reflectionGap,?deafalutPaint);??

??

????canvas.drawBitmap(reflectionImage,?0,?h?+?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,?h,?w,?bitmapWithReflection.getHeight()??

????????????+?reflectionGap,?paint);??

??

????return?bitmapWithReflection;??

}??

?三、Drawable

1、Bitmap轉換成Drawable

Java代碼??

Bitmap?bm=xxx;?//xxx根據你的情況獲取??

BitmapDrawable?bd=?new?BitmapDrawable(getResource(),?bm);???

因為BtimapDrawable是Drawable的子類，最終直接使用bd對象即可。??

2、Drawable縮放

Java代碼??

public?static?Drawable?zoomDrawable(Drawable?drawable,?int?w,?int?h)?{??

????int?width?=?drawable.getIntrinsicWidth();??

????int?height?=?drawable.getIntrinsicHeight();??

????//?drawable轉換成bitmap??

????Bitmap?oldbmp?=?drawableToBitmap(drawable);??

????//?創建操作圖片用的Matrix對象??

????Matrix?matrix?=?new?Matrix();??

????//?計算縮放比例??

????float?sx?=?((float)?w?/?width);??

????float?sy?=?((float)?h?/?height);??

????//?設置縮放比例??

????matrix.postScale(sx,?sy);??

????//?建立新的bitmap，其內容是對原bitmap的縮放后的圖??

????Bitmap?newbmp?=?Bitmap.createBitmap(oldbmp,?0,?0,?width,?height,??

????????????matrix,?true);??

????return?new?BitmapDrawable(newbmp);??

}??

?

轉載于:https://www.cnblogs.com/siyiganshou/archive/2012/08/15/2639700.html

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