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：
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：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ImageView
android:id="@+id/image01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10px"
/>
<ImageView
android:id="@+id/image02"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10px"
/>
</LinearLayout>
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：
OK大功告成了!!
