《Android高手进阶教程》22.Android中几种图像特效处理的集锦

大家好,这一节给大家分享的是Android图像特效处理的小技巧,比如圆角、倒影、还有就是图片缩放、Drawable转化为Bitmap、Bitmap转化为Drawable等等。

废话少说,直接讲解今天的实例,本例主要是先获取壁纸(getWallpaper()),然后对当前壁纸的一些特效处理。大家按步骤一步一步来:

第一步:新建一个Android工程命名为ImageDemo,工程结构如下:

ImageDemo

第二步:新建一个.java文件,命名为ImageUtil.java,在里面定义一些图片处理方法,代码如下:

package com.android.tutor;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Bitmap.Config;
import android.graphics.PorterDuff.Mode;
import android.graphics.Shader.TileMode;
import android.graphics.drawable.Drawable;

public class ImageUtil {

	// 放大缩小图片
	public static Bitmap zoomBitmap(Bitmap bitmap, int w, int h) {
		int width = bitmap.getWidth();
		int height = bitmap.getHeight();
		Matrix matrix = new Matrix();
		float scaleWidht = ((float) w / width);
		float scaleHeight = ((float) h / height);
		matrix.postScale(scaleWidht, scaleHeight);
		Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height,
				matrix, true);
		return newbmp;
	}

	// 将Drawable转化为Bitmap
	public static Bitmap drawableToBitmap(Drawable drawable) {
		int width = drawable.getIntrinsicWidth();
		int height = drawable.getIntrinsicHeight();
		Bitmap bitmap = Bitmap.createBitmap(width, height, drawable
				.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
				: Bitmap.Config.RGB_565);
		Canvas canvas = new Canvas(bitmap);
		drawable.setBounds(0, 0, width, height);
		drawable.draw(canvas);
		return bitmap;

	}

	// 获得圆角图片的方法
	public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float roundPx) {

		Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
				bitmap.getHeight(), Config.ARGB_8888);
		Canvas canvas = new Canvas(output);

		final int color = 0xff424242;
		final Paint paint = new Paint();
		final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
		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;
	}

	// 获得带倒影的图片方法
	public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap) {
		final int reflectionGap = 4;
		int width = bitmap.getWidth();
		int height = bitmap.getHeight();

		Matrix matrix = new Matrix();
		matrix.preScale(1, -1);

		Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, height / 2,
				width, height / 2, matrix, false);

		Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
				(height + height / 2), Config.ARGB_8888);

		Canvas canvas = new Canvas(bitmapWithReflection);
		canvas.drawBitmap(bitmap, 0, 0, null);
		Paint deafalutPaint = new Paint();
		canvas.drawRect(0, height, width, height + reflectionGap, deafalutPaint);

		canvas.drawBitmap(reflectionImage, 0, height + 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, height, width, bitmapWithReflection.getHeight()
				+ reflectionGap, paint);

		return bitmapWithReflection;
	}

}

第三步:修改main.xml布局文件,主要放了两个ImageView控件,代码如下:

第四步:修改主核心程序,ImageDemo.java,代码如下:

package com.android.tutor;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.widget.ImageView;

public class Imagedemo extends Activity {
	
	private ImageView mImageView01, mImageView02;

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		setupViews();
	}

	private void setupViews() {
		
		mImageView01 = (ImageView) findViewById(R.id.image01);
		mImageView02 = (ImageView) findViewById(R.id.image02);

		// 获取壁纸返回值是Drawable
		Drawable drawable = getWallpaper();
		// 将Drawable转化为Bitmap
		Bitmap bitmap = ImageUtil.drawableToBitmap(drawable);
		// 缩放图片
		Bitmap zoomBitmap = ImageUtil.zoomBitmap(bitmap, 100, 100);
		// 获取圆角图片
		Bitmap roundBitmap = ImageUtil
				.getRoundedCornerBitmap(zoomBitmap, 10.0f);
		// 获取倒影图片
		Bitmap reflectBitmap = ImageUtil
				.createReflectionImageWithOrigin(zoomBitmap);
		// 这里可以让Bitmap再转化为Drawable
		// Drawable roundDrawable = new BitmapDrawable(roundBitmap);
		// Drawable reflectDrawable = new BitmapDrawable(reflectBitmap);
		// mImageView01.setBackgroundDrawable(roundDrawable);
		// mImageView02.setBackgroundDrawable(reflectDrawable);

		mImageView01.setImageBitmap(roundBitmap);
		mImageView02.setImageBitmap(reflectBitmap);
	}

}

第五步:运行上述工程,查看效果如下:

ImageDemo效果

OK大功告成了!!

本文参考文献:http://wiki.impjq.net/doku.php?id=code:android-code:image-convert&rev=1275640889&mddo=print

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