Drawable与 Bitmap 转换总结

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Drawable 使用方法详解请看上篇文章.

Drawable 使用方法详解

本篇文章主要介绍 Android 开发中的部分知识点，通过阅读本篇文章，您将收获以下内容:

1. 从资源中获取Bitmap
2. Bitmap ----> byte[]
3. byte[] ----> Bitmap
4. Bitmap 缩放方法
5. Drawable ----> Bitmap
6. 圆角图片
7. 获取带倒影的图片
8. bitmap ----> Drawable
9. drawable缩放 ，先转 bitmap 后缩放

1. 从资源中获取Bitmap

	// 1.从资源中获取Bitmap

	public void UseBitmap(Context context, ImageView imageView, int drawableId) {

		Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),

				drawableId);

		imageView.setImageBitmap(bitmap);

	}

2. Bitmap ----> byte[]

	// 2.Bitmap ---> byte[]

	public byte[] BitmapToBytes(Bitmap bitmap) {

		ByteArrayOutputStream baos = new ByteArrayOutputStream();

		bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);

		return baos.toByteArray();

	}

3. byte[] ----> Bitmap

	// 3.byte[] ---->bitmap

	public Bitmap BytesToBitmap(byte[] b) {

		if (b.length != 0) {

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

		} else {

			return null;

		}

	}

4. Bitmap 缩放方法

	// 4.Bitmap 缩放方法

	public static Bitmap ZoomBitmap(Bitmap bitmap, int width, int heigh) {

		int w = bitmap.getWidth();

		int h = bitmap.getHeight();

		Matrix matrix = new Matrix();

		float scalewidth = (float) width / w;

		float scaleheigh = (float) heigh / h;

		matrix.postScale(scalewidth, scaleheigh);

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

		return newBmp;

	}

5. Drawable ----> Bitmap

	// 5. Drawable----> Bitmap

	public static Bitmap DrawableToBitmap(Drawable drawable) {

		// 获取 drawable 长宽

		int width = drawable.getIntrinsicWidth();

		int heigh = drawable.getIntrinsicHeight();

		drawable.setBounds(0, 0, width, heigh);

		// 获取drawable的颜色格式

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

				: Bitmap.Config.RGB_565;

		// 创建bitmap

		Bitmap bitmap = Bitmap.createBitmap(width, heigh, config);

		// 创建bitmap画布

		Canvas canvas = new Canvas(bitmap);

		// 将drawable 内容画到画布中

		drawable.draw(canvas);

		return bitmap;

	}

6. 圆角图片

-实现效果如下：

• 实现代码如下：

	// 6.圆角图片

	public static Bitmap SetRoundCornerBitmap(Bitmap bitmap, float roundPx) {

		int width = bitmap.getWidth();

		int heigh = bitmap.getHeight();

		// 创建输出bitmap对象

		Bitmap outmap = Bitmap.createBitmap(width, heigh,

				Bitmap.Config.ARGB_8888);

		Canvas canvas = new Canvas(outmap);

		final int color = 0xff424242;

		final Paint paint = new Paint();

		final Rect rect = new Rect(0, 0, width, heigh);

		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(PorterDuff.Mode.SRC_IN));

		canvas.drawBitmap(bitmap, rect, rect, paint);

		return outmap;

	}

7. 获取带倒影的图片

• 实现效果如下：

• 实现代码如下：

	// 7.获取带倒影的图片

	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),

				Bitmap.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, Shader.TileMode.CLAMP);

		paint.setShader(shader);

		// Set the Transfer mode to be porter duff and destination in

		paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));

		// Draw a rectangle using the paint with our linear gradient

		canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()

				+ reflectionGap, paint);

		return bitmapWithReflection;

	}

8. bitmap ----> Drawable

	// 8. bitmap ---Drawable

	public static Drawable BitmapToDrawable(Bitmap bitmap, Context context) {

		BitmapDrawable drawbale = new BitmapDrawable(context.getResources(),

				bitmap);

		return drawbale;

	}

9. drawable缩放 ，先转 bitmap 后缩放

drawable 缩放 ，先转 bitmap ，调用 5 中的方法 后缩放。

	// 9. drawable进行缩放 ---> bitmap 然后比对bitmap进行缩放

	public static Drawable ZoomDrawable(Drawable drawable, int w, int h) {

		int width = drawable.getIntrinsicWidth();

		int height = drawable.getIntrinsicHeight();

		// 调用5 中 drawable转换成bitmap

		Bitmap oldbmp = DrawableToBitmap(drawable);

		// 创建操作图片用的Matrix对象

		Matrix matrix = new Matrix();

		// 计算缩放比例

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

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

		// 设置缩放比例

		matrix.postScale(sx, sy);

		// 建立新的bitmap，其内容是对原bitmap的缩放后的图

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

				matrix, true);

		return new BitmapDrawable(newbmp);

	}

至此，本篇已结束，如有不对的地方，欢迎您的建议与指正。同时期待您的关注，感谢您的阅读，谢谢！