Android基础：ImageView

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本文介绍Android中ImageView的ScaleType属性及图像特效处理方法，包括图片缩放、圆角处理、倒影效果等，并提供示例代码。

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scaletype之centerInside,center,centerCrop,fitCenter之间的区别

ImageView.ScaleType|android:scaleType值的意义：

ImageView.ScaleType.CENTER|android:scaleType="center"
按图片的原来size居中显示，当图片长/宽超过View的长/宽，则截取图片的居中部分显示

ImageView.ScaleType.CENTER_CROP|android:scaleType="centerCrop"
按比例扩大图片的size居中显示，使得图片长 (宽)等于或大于View的长(宽)

ImageView.ScaleType.CENTER_INSIDE|android:scaleType="centerInside"
将图片的内容完整居中显示，通过按比例缩小或原来的size使得图片长(宽)等于或小于View的长(宽)

ImageView.ScaleType.FIT_CENTER|android:scaleType="fitCenter"

把图片按比例扩大(缩小)到View的宽度，居中显示

ImageView.ScaleType.FIT_END|android:scaleType="fitEnd"
把图片按比例扩大(缩小)到View的宽度，显示在View的下部分位置

ImageView.ScaleType.FIT_START|android:scaleType="fitStart"
把图片按比例扩大(缩小)到View的宽度，显示在View的上部分位置

ImageView.ScaleType.FIT_XY|android:scaleType="fitXY"
把图片按照指定的大小在View中显示

ImageView.ScaleType.MATRIX|android:scaleType="matrix"
用matrix来绘制

这里写图片描述

drawable –缩放，圆角,倒影

转载：http://blog.youkuaiyun.com/android_tutor/article/details/5981753
大家好,这一节给大家分享的是Android中几种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.
废话少说了,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:
效果图
这里写图片描述
1 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

public class ImageUtil {

    // 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;

    }

    // 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;
    }

    // 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;
    }

}

2 mainActivity 中使用

public class MainActivity extends Activity {

    private ImageView mImageView01, mImageView02;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        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, 200, 200);
        // 获取圆角图片
        Bitmap roundBitmap = ImageUtil.getRoundedCornerBitmap(zoomBitmap, 1000.0f);//100是圆角度
        // 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);
    }
}

源码：
http://download.youkuaiyun.com/detail/ss1168805219/9493007

利用limageLoader.jar实现圆形

根据图片的url加载圆形图片。
地址：http://blog.youkuaiyun.com/ss1168805219/article/details/51084239

ImageSwitch

效果图

这里写图片描述

使用步骤

ImageSwitcher和TextSwitcher的使用步骤是一样的
- 设置Factory
- 设置进出动画
- 设置初始值
- 改变当前值

方法：

setFactory(...)
setInAnimation(int slide_in)
setOutAnimation(int slide_out)
setImageResource(imgArray[i])

xml

<ImageSwitcher
    android:id="@+id/imgSwitch"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

完整代码

btn = (Button) findViewById(R.id.btn);
imageSwitcher = (ImageSwitcher) findViewById(R.id.imgSwitch);

imageSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
    @Override
    public View makeView() {
        ImageView imageView = new ImageView(context);
        return imageView;
    }
});
Animation slide_in = AnimationUtils.loadAnimation(context, android.R.anim.slide_in_left);
Animation slide_out = AnimationUtils.loadAnimation(context, android.R.anim.slide_out_right);
imageSwitcher.setInAnimation(slide_in);
imageSwitcher.setOutAnimation(slide_out);
imageSwitcher.setImageResource(imgArray[0]);

btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int i = (++index) % imgArray.length;
        imageSwitcher.setImageResource(imgArray[i]);
    }
});