Android中Bitmap和Drawable

转载 于 2014-01-02 15:47:07 发布 · 634 阅读 · 0

本文介绍了Android中Bitmap和Drawable的使用方法，包括从资源获取Bitmap、Bitmap与byte数组之间的转换、Bitmap的缩放及圆角处理等。同时，文章还讲解了如何将Bitmap转换为Drawable以及Drawable的缩放方法。

摘要生成于 C知道 ，由 DeepSeek-R1 满血版支持， 前往体验 >

Android中Bitmap和Drawable           
Android 

一、相关概念

1、Drawable就是一个可画的对象，其可能是一张位图（BitmapDrawable），也可能是一个图形（ShapeDrawable），还有可能是一个图层（LayerDrawable），我们根据画图的需求，创建相应的可画对象
2、Canvas画布，绘图的目的区域，用于绘图
3、Bitmap位图，用于图的处理
4、Matrix矩阵

二、Bitmap

1、从资源中获取Bitmap
Java代码

Resources res = getResources();  

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

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

 

2、Bitmap → byte[]
Java代码

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();
	}
 3、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;
		}
	}
4、Bitmap缩放

public static Bitmap drawableToBitmap(Drawable drawable) {
  // 取 drawable 的长宽
  int w = drawable.getIntrinsicWidth();
  int h = drawable.getIntrinsicHeight();

  // 取 drawable 的颜色格式
  Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
    : Bitmap.Config.RGB_565;
  // 建立对应 bitmap
  Bitmap bitmap = Bitmap.createBitmap(w, h, config);
  // 建立对应 bitmap 的画布
  Canvas canvas = new Canvas(bitmap);
  drawable.setBounds(0, 0, w, h);
  // 把 drawable 内容画到画布中
  drawable.draw(canvas);
  return bitmap;
 }

	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、将Drawable转化为Bitmap
Java代码

 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 drawableToBitmap(Drawable drawable) {
		// 取 drawable 的长宽
		int w = drawable.getIntrinsicWidth();
		int h = drawable.getIntrinsicHeight();

		// 取 drawable 的颜色格式
		Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
				: Bitmap.Config.RGB_565;
		// 建立对应 bitmap
		Bitmap bitmap = Bitmap.createBitmap(w, h, config);
		// 建立对应 bitmap 的画布
		Canvas canvas = new Canvas(bitmap);
		drawable.setBounds(0, 0, w, h);
		// 把 drawable 内容画到画布中
		drawable.draw(canvas);
		return bitmap;
	}
6、获得圆角图片 
Java代码
  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. }  
	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、获得带倒影的图片
Java代码

 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;
	}

 三、Drawable

1、Bitmap转换成Drawable
Java代码:
Bitmap bm=xxx; //xxx根据你的情况获取
BitmapDrawable bd= new BitmapDrawable(getResource(), bm);
因为BtimapDrawable是Drawable的子类，最终直接使用bd对象即可。   
Bitmap bm=xxx; //xxx根据你的情况获取
BitmapDrawable bd= new BitmapDrawable(getResource(), bm); 
因为BtimapDrawable是Drawable的子类，最终直接使用bd对象即可。
2、Drawable缩放
 public static Drawable zoomDrawable(Drawable drawable, int w, int h) {
  int width = drawable.getIntrinsicWidth();
  int height = drawable.getIntrinsicHeight();
  // 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);
 }
 
 

原文链接：http://dyh7077063.iteye.com/blog/970672

 

/**
     * Drawable 转 bitmap
     * @param drawable
     * @return
     */ 
    public static Bitmap drawable2Bitmap(Drawable drawable){ 
        if(drawable instanceof BitmapDrawable){ 
            return ((BitmapDrawable)drawable).getBitmap() ; 
        }else if(drawable instanceof NinePatchDrawable){ 
            Bitmap bitmap = Bitmap 
                    .createBitmap( 
                            drawable.getIntrinsicWidth(), 
                            drawable.getIntrinsicHeight(), 
                            drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 
                                    : Bitmap.Config.RGB_565); 
            Canvas canvas = new Canvas(bitmap); 
            drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), 
                    drawable.getIntrinsicHeight()); 
            drawable.draw(canvas); 
            return bitmap; 
        }else{ 
            return null ; 
        } 
    } 

AndroidLiuBin
关注
评论
添加红包

请填写红包祝福语或标题

个

红包个数最小为10个

元

红包金额最低5元

当前余额3.43元 前往充值 >
需支付：10.00元
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付元
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明：

1.余额是钱包充值的虚拟货币，按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载，可以购买VIP、付费专栏及课程。

余额充值