自定义控件-----CoverFlow

 

 

 

CoverFlow--我也不知道为什么要叫这个名字,貌似是从iphone上继承过来的?

随便了,反正就是这个样子了

 

 

此控件的设计和实现思路和部分代码同样是剽窃某网站上的,因为时间太久了,找不到原文地址了..杯具,所以我才来做备份的.

此类是从Gallery继承过来的,用法自然也就和Gallery一样了

 

程序的背景是一个xml陪的渐变背景,具体可以参看另外一篇"渐变背景"的文章

图片的倒影效果是适用了ReflectionImage控件,具体可以参看上一篇博文.

 

 

先看代码吧,看了代码什么都明白了

package com.myview;
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;
public class CoverFlow extends Gallery {
	
	private Camera mCamera = new Camera();
	private int mMaxRotationAngle = 50;
	private int mMaxZoom = -380;
	private int mCoveflowCenter;
	private boolean mAlphaMode = true;
	private boolean mCircleMode = false;
	public CoverFlow(Context context) {
		super(context);
		this.setStaticTransformationsEnabled(true);
	}
	public CoverFlow(Context context, AttributeSet attrs) {
		super(context, attrs);
		this.setStaticTransformationsEnabled(true);
	}
	public CoverFlow(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		this.setStaticTransformationsEnabled(true);
	}
	public int getMaxRotationAngle() {
		return mMaxRotationAngle;
	}
	public void setMaxRotationAngle(int maxRotationAngle) {
		mMaxRotationAngle = maxRotationAngle;
	}
	public boolean getCircleMode() {
		return mCircleMode;
	}
	public void setCircleMode(boolean isCircle) {
		mCircleMode = isCircle;
	}
	public boolean getAlphaMode() {
		return mAlphaMode;
	}
	public void setAlphaMode(boolean isAlpha) {
		mAlphaMode = isAlpha;
	}
	public int getMaxZoom() {
		return mMaxZoom;
	}
	public void setMaxZoom(int maxZoom) {
		mMaxZoom = maxZoom;
	}
	private int getCenterOfCoverflow() {
		return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2
				+ getPaddingLeft();
	}
	private static int getCenterOfView(View view) {
		return view.getLeft() + view.getWidth() / 2;
	}
	protected boolean getChildStaticTransformation(View child, Transformation t) {
		final int childCenter = getCenterOfView(child);
		final int childWidth = child.getWidth();
		int rotationAngle = 0;
		t.clear();
		t.setTransformationType(Transformation.TYPE_MATRIX);
		if (childCenter == mCoveflowCenter) {
			transformImageBitmap((ImageView) child, t, 0);
		} else {
			rotationAngle = (int) (((float) (mCoveflowCenter - childCenter) / childWidth) * mMaxRotationAngle);
			if (Math.abs(rotationAngle) > mMaxRotationAngle) {
				rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle
						: mMaxRotationAngle;
			}
			transformImageBitmap((ImageView) child, t, rotationAngle);
		}
		return true;
	}
	/**
	 * This is called during layout when the size of this view has changed. If
	 * you were just added to the view hierarchy, you're called with the old
	 * values of 0.
	 * 
	 * @param w
	 *            Current width of this view.
	 * @param h
	 *            Current height of this view.
	 * @param oldw
	 *            Old width of this view.
	 * @param oldh
	 *            Old height of this view.
	 */
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		mCoveflowCenter = getCenterOfCoverflow();
		super.onSizeChanged(w, h, oldw, oldh);
	}
	/**
	 * Transform the Image Bitmap by the Angle passed
	 * 
	 * @param imageView
	 *            ImageView the ImageView whose bitmap we want to rotate
	 * @param t
	 *            transformation
	 * @param rotationAngle
	 *            the Angle by which to rotate the Bitmap
	 */
	private void transformImageBitmap(ImageView child, Transformation t,
			int rotationAngle) {
		mCamera.save();
		final Matrix imageMatrix = t.getMatrix();
		final int imageHeight = child.getLayoutParams().height;
		final int imageWidth = child.getLayoutParams().width;
		final int rotation = Math.abs(rotationAngle);
		mCamera.translate(0.0f, 0.0f, 100.0f);
		// As the angle of the view gets less, zoom in
		if (rotation <= mMaxRotationAngle) {
			float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));
			mCamera.translate(0.0f, 0.0f, zoomAmount);
			if (mCircleMode) {
				if (rotation < 40)
					mCamera.translate(0.0f, 155, 0.0f);
				else
					mCamera.translate(0.0f, (255 - rotation * 2.5f), 0.0f);
			}
			if (mAlphaMode) {
				((ImageView) (child)).setAlpha((int) (255 - rotation * 2.5));
			}
		}
		mCamera.rotateY(rotationAngle);
		mCamera.getMatrix(imageMatrix);
		imageMatrix.preTranslate(-(imageWidth / 2), -(imageHeight / 2));
		imageMatrix.postTranslate((imageWidth / 2), (imageHeight / 2));
		mCamera.restore();
	}
}

 

这个就是CoverFlow类,说明几点

1. 成员函数

    mCamera是用来做类3D效果处理,比如z轴方向上的平移,绕y轴的旋转等

    mMaxRotationAngle是图片绕y轴最大旋转角度,也就是屏幕最边上那两张图片的旋转角度

    mMaxZoom是图片在z轴平移的距离,视觉上看起来就是放大缩小的效果.

    其他的变量都可以无视

 

2. 构造函数里面的setStaticTransformationsEnabled

protected void setStaticTransformationsEnabled (boolean enabled)

When this property is set to true, this ViewGroup supports static transformations on children; this causes getChildStaticTransformation(View, android.view.animation.Transformation) to be invoked when a child is drawn. Any subclass overriding getChildStaticTransformation(View, android.view.animation.Transformation) should set this property to true.

Parameters

enabled	True to enable static transformations on children, false otherwise.

 

也就是说把这个属性设成true的时候每次viewGroup(看Gallery的源码就可以看到它是从ViewGroup间接继承过来的)在重新画它的child的时候都会促发getChildStaticTransformation这个函数,所以我们只需要在这个函数里面去加上旋转和放大的操作就可以了

 

其他的getter和setter函数都可以无视

 

 

 

package com.hello;
import com.hello.R;
import com.myview.*;
import android.app.Activity;
import android.content.Context;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
public class HelloAndroid extends Activity {
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		CoverFlow cf = new CoverFlow(this); 
		cf.setBackgroundResource(R.drawable.shape);
		cf.setAdapter(new ImageAdapter(this)); 
		ImageAdapter imageAdapter = new ImageAdapter(this);
		cf.setAdapter(imageAdapter);
//		cf.setAlphaMode(false); 
//		cf.setCircleMode(false);
//		cf.setSelection(3, true);  
		cf.setAnimationDuration(1000);
		setContentView(cf);
	}
	
	
	
	public class ImageAdapter extends BaseAdapter {
		int mGalleryItemBackground;
		private Context mContext;
		private Integer[] mImageIds = { 
				R.drawable.a, 
				R.drawable.b,
				R.drawable.d,
				R.drawable.e,
				R.drawable.c};
		
		public ImageAdapter(Context c) {
			mContext = c;
		}
		public int getCount() {
			return mImageIds.length;
		}
		public Object getItem(int position) {
			return position; 
		}
		public long getItemId(int position) {
			return position;
		}
		public View getView(int position, View convertView, ViewGroup parent) {
			ReflectionImage i = new ReflectionImage(mContext);
			
			i.setImageResource(mImageIds[position]);
			i.setLayoutParams(new CoverFlow.LayoutParams(96, 76));
			i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
			// Make sure we set anti-aliasing otherwise we get jaggies
			BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();
			drawable.setAntiAlias(true);
			return i;
		}
 
		public float getScale(boolean focused, int offset) {
			return Math.max(0, 1.0f / (float) Math.pow(2, Math.abs(offset)));
		}
	}
}

 

BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();

drawable.setAntiAlias(true);

是保证图片绕Y旋转了以后不会出现锯齿