Drawable 和 Bitmap(轉)

1、相關概念

一、Drawable就是一個可畫的對象，其多是一張位圖（BitmapDrawable），也多是一個圖形（ShapeDrawable），還有多是一個圖層（LayerDrawable），咱們根據畫圖的需求，建立相應的可畫對象

二、Canvas畫布，繪圖的目的區域，用於繪圖

三、Bitmap位圖，用於圖的處理

四、Matrix矩陣

2、Bitmap

一、從資源中獲取Bitmap

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

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

二、Bitmap → byte[]

public byte[] Bitmap2Bytes(Bitmap bm) {
 ByteArrayOutputStream baos = new ByteArrayOutputStream();
 bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
 return baos.toByteArray();
}

public byte[] Bitmap2Bytes(Bitmap bm) {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
		return baos.toByteArray();
	}

三、byte[] → Bitmap

public Bitmap Bytes2Bimap(byte[] b) {
 if (b.length != 0) {
 return BitmapFactory.decodeByteArray(b, 0, b.length);
 } else {
 return null;
 }
}

public Bitmap Bytes2Bimap(byte[] b) {
		if (b.length != 0) {
			return BitmapFactory.decodeByteArray(b, 0, b.length);
		} else {
			return null;
		}
	}

四、Bitmap縮放

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;
}

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;
	}

五、將Drawable轉化爲Bitmap

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;
 // 創建對應 bitmap
 Bitmap bitmap = Bitmap.createBitmap(w, h, config);
 // 創建對應 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;
 }

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;
		// 創建對應 bitmap
		Bitmap bitmap = Bitmap.createBitmap(w, h, config);
		// 創建對應 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;
	}

六、得到圓角圖片

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;
}

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;
	}

七、得到帶倒影的圖片

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;
}

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;
	}

3、Drawable

一、Bitmap轉換成Drawable

Bitmap bm=xxx; //xxx根據你的狀況獲取
BitmapDrawable bd= new BitmapDrawable(getResource(), bm);
由於BtimapDrawable是Drawable的子類，最終直接使用bd對象便可。

Bitmap bm=xxx; //xxx根據你的狀況獲取
BitmapDrawable bd= new BitmapDrawable(getResource(), bm); 
由於BtimapDrawable是Drawable的子類，最終直接使用bd對象便可。

二、Drawable縮放

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);
 // 建立操做圖片用的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);
 // 創建新的bitmap，其內容是對原bitmap的縮放後的圖
 Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
 matrix, true);
 return new BitmapDrawable(newbmp);
}