[view] 11_3DGallery图库 - Android 4.0 Documentation

一、倒影、遮罩、渐变、抗锯齿、合成1、定义一个类 CustomeGallery继承Gallery
2、将资源图片转成Bitmap
3、进行翻转，合成，保存到一个List
4、通过ListView展示出来
5、代码：
ImageAdapter.java

package cn.zengfansheng.customeGallery.adapter;
 
import java.util.ArrayList;
import java.util.List;
 
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.Shader;
import android.graphics.Shader.TileMode;
import android.graphics.drawable.BitmapDrawable;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Gallery.LayoutParams;
import android.widget.ImageView;
 
public class ImageAdapter extends BaseAdapter {
 
    private Context context;
    private int[] imageIds;
    private List<ImageView> imageViews;
 
    public ImageAdapter(Context context, int[] imageIds) {
        this.context = context;
        this.imageIds = imageIds;
        imageViews = new ArrayList<ImageView>();
 
    }
 
    /**
     * 生成倒影的图片，并合成
     */
    public void getInvertImage() {
 
        int interval = 5;//间隔，原始图片和倒影图片的间隔
 
        for (int i = 0; i < imageIds.length; i++) {
 
            //1、获取原始bitmap
            Bitmap resourceBitmap = BitmapFactory.decodeResource(context.getResources(), imageIds[i]);
 
            // 原始bitmap的宽高
            int width = resourceBitmap.getWidth();
            int height = resourceBitmap.getHeight();
 
            //2、获取倒影bitmap
            Matrix matrix = new Matrix();
            float[] values = new float[]{
                    1,0,0,
                    0,-1,resourceBitmap.getHeight(),
                    0,0,1
            };
            matrix.setValues(values);
            // matrix.setRotate(180, 1, -1);
            //倒影的bitmap
            Bitmap invertBitmap = Bitmap.createBitmap(resourceBitmap,0,height/2,width,height/2, matrix, false);
 
            //3、创建一个空的bitmap
            Config config = Config.ARGB_8888;// 4B表示一个像素
            Bitmap resultBitmap = Bitmap.createBitmap(width, (int) (height * 1.5 + 10), config);
 
            // 4、用画笔在这空白的bitmap上画
            Canvas canvas = new Canvas(resultBitmap);
 
            // 4-1画原始bitmap
            Paint defaultPaint = new Paint();
            canvas.drawBitmap(resourceBitmap, 0, 0, defaultPaint);
 
            // 画个矩形间隔
            canvas.drawRect(0, height, width, height + interval, defaultPaint);
 
            // 4-2画倒影的bimmap
            canvas.drawBitmap(invertBitmap, 0, height + interval, defaultPaint);
 
            // 5、设置给ImageView并抗锯齿
            BitmapDrawable bitmapDrawable = new BitmapDrawable(context.getResources(), resultBitmap);
            bitmapDrawable.setAntiAlias(true);// 抗锯齿，平滑效果
 
            ImageView iv = new ImageView(context);
            iv.setImageDrawable(bitmapDrawable);
 
            // 7、设置显示图片的大小
            @SuppressWarnings("deprecation")
            LayoutParams params = new LayoutParams(160, 320);
            iv.setLayoutParams(params);
 
            // 8、遮罩
            Paint paint = new Paint();
            paint.setXfermode(new PorterDuffXfermode(android.graphics.PorterDuff.Mode.DST_IN));
 
            // 9、渐变
            Shader shader = new LinearGradient(0, height, 0, resultBitmap.getHeight(),0x70ffffff, 0x00ffffff, TileMode.CLAMP);
            paint.setShader(shader );
            canvas.drawRect(0, height, width, resultBitmap.getHeight(), paint);
 
            // 10、加到集合中去
            imageViews.add(iv);
 
        }
    }
 
    @Override
    public int getCount() {
        if (imageViews != null) {
            return imageViews.size();// 擦，没有return
        }
        return 0;
    }
 
    @Override
    public Object getItem(int position) {
        return null;
    }
 
    @Override
    public long getItemId(int position) {
        return position;
    }
 
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return imageViews.get(position);
    }
}

二、变形
CustomeGallery.java

package cn.zengfansheng.customeGallery.view;

import android.content.Context;

import android.graphics.Camera;

import android.graphics.Matrix;

import android.util.AttributeSet;

import android.view.View;

import android.view.animation.Transformation;

import android.widget.Gallery;

import android.widget.ImageView;

/**

* 自定义的Gallery

* @author hacket

*/

@SuppressWarnings("deprecation")

public class CustomeGallery extends Gallery {

private int currentCenterOfGallery;// 展示图片的中心点

public CustomeGallery(Context context, AttributeSet attrs) {

super(context, attrs);

setStaticTransformationsEnabled(true);// 可以转化(变形)

}

public CustomeGallery(Context context,int[] imageIds) {

super(context);

setStaticTransformationsEnabled(true);// 可以转化(变形)

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

super.onSizeChanged(w, h, oldw, oldh);

currentCenterOfGallery = getCurrentCenterOfGallery();

}

// 1、获取grallery展示图片的中心点

public int getCurrentCenterOfGallery(){

// （grallery宽度-左边paddingLeft-右边paddingRigth）/2+左边paddingLeft

// getLeft()+getWidth()/2;

return (getWidth()-getPaddingLeft()-getPaddingRight())/2+getPaddingLeft();

}

// 2、获取图片的中心点

public int getCurrentCenterOfView(View view) {

return view.getLeft() + view.getWidth() / 2;

}

// 3、

@Override

protected boolean getChildStaticTransformation(View child, Transformation t) {

// 得到图片的中心点

int currentOfChild = getCurrentCenterOfView(child);

int childHeight = child.getLayoutParams().height;

int childWidth = child.getLayoutParams().width;

int rotateAngle = 0;// 旋转的角度

t.clear();// 清理之前的转换

// 图片变形的风格样式

t.setTransformationType(Transformation.TYPE_MATRIX);

if (currentOfChild == currentCenterOfGallery) {

// 是中心位置，旋转角度为0

transformationBitmap((ImageView) child, t, 0);

} else {

// 不是中心位置

rotateAngle = (int) ((float)(currentCenterOfGallery - currentOfChild) /childWidth * maxRotateAngle);

if(Math.abs(rotateAngle) > maxRotateAngle){//旋转角度绝对值大于最大等于maxRotateAngle

rotateAngle = rotateAngle < 0 ? -maxRotateAngle : maxRotateAngle;

}

transformationBitmap((ImageView) child, t, rotateAngle);

}

return true;

}

private Camera camera = new Camera();

private int maxZoom = -250;//最大缩放值

private int maxRotateAngle = 50;//最大旋转角度

// 图片变形

private void transformationBitmap(ImageView child,Transformation t,int rotateAngle){

camera.save();//保存

Matrix imageMatrix = t.getMatrix();

int rotate = Math.abs(rotateAngle);

int imageWidth = child.getWidth();

int imageHeight = child.getHeight();

//z轴正数图片放大

//x水平移动， y垂直移动

camera.translate(0.0f, 0.0f, 100.0f);

if (rotate < maxRotateAngle) {

float zoom = (float) ((rotate * 1.5) + maxZoom);

camera.translate(0.0f, 0.0f, zoom);

child.setAlpha((int) (255 - rotate * 2.5));

}

// 图片向展示中心进行垂直角度的旋转

camera.rotateY(rotateAngle);

camera.getMatrix(imageMatrix);

// Preconcats matrix相当于右乘矩阵

// Postconcats matrix相当于左乘矩阵。

imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));

imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));

camera.restore();// 还原

}

OOM问题：如果加载的图片过多，内存会溢出，程序崩溃
使用软引用
SoftReference()来包裹ImageView

System.gc() 通知垃圾回收器回收垃圾
问题1：每次都要暂停那么几十ms(看log)
问题2：只是显示说明要调用垃圾回收器来回收垃圾，但并不能保证立刻就运行垃圾回收器来回收垃圾
Indicates to the VM that it would be a good time to run the garbage collector. Note that this is a hint only. There is no guarantee that the garbage collector will actually be run.

解决OOM问题：如果加载的图片过多，会导致OOM溢出

解决：使用软引用SoftReference,
a) new出来一个map用来存储软引用对象
private Map<Integer, SoftReference<ImageView>> map = new HashMap<Integer, SoftReference<ImageView>>();
b)将ImageView对象存储到软引用中去

public void intiImageView(){

for (int i = 0; i < imageIds.length; i++) {

// 通过id获取倒影合成的ImageView

ImageView invertImageView = getInvertImage(imageIds[i]);

// 用一个软引用关联该倒影ImageView

SoftReference<ImageView> softReferenceIV = new SoftReference<ImageView>(invertImageView);

// 将该软引用加到map中去

map.put(i, softReferenceIV);

}

}
c) 从软引用中获取ImageView，get()，如果返回null，说明已经被垃圾回收器给回收了，
不为null的话，那么为该ImageView对象

// 从集合中获取指定位置的软引用

SoftReference<ImageView> ivSoftReference = map.get(position);

// 获取该软引用引用的对象

ImageView imageView = ivSoftReference.get();//得到所引用的对象，如果为null,表示已经被垃圾回收器回收

if (imageView == null) {// 如果为null,说明已经被回收，那么重新创建一个

Log.i(TAG, "回收对象："+position);

imageView = getInvertImage(imageIds[position]);

}

// 否则，用该软引用所引用的对象

return imageView;
结果：
可以看到，当到了15后，14,13直接从软引用中get()数据了，而不是重新创建对象