Android实现CoverFlow效果二

001 package com.coverflow;

002

003 import android.content.Context;

004 import android.graphics.Camera;

005 import android.graphics.Matrix;

006 import android.util.AttributeSet;

007 import android.view.View;

008 import android.view.animation.Transformation;

009 import android.widget.Gallery;

010 import android.widget.ImageView;

011

012 public class CoverFlow extends Gallery {

013

014 private Camera mCamera = new Camera();

015 private int mMaxRotationAngle = 50;

016 private int mMaxZoom = -380;

017 private int mCoveflowCenter;

018 private boolean mAlphaMode = true;

019 private boolean mCircleMode = false;

020

021 public CoverFlow(Context context) {

022 super(context);

023 this.setStaticTransformationsEnabled(true);

024 }

025

026 public CoverFlow(Context context, AttributeSet attrs) {

027 super(context, attrs);

028 this.setStaticTransformationsEnabled(true);

029 }

030

031 public CoverFlow(Context context, AttributeSet attrs, int defStyle) {

032 super(context, attrs, defStyle);

033 this.setStaticTransformationsEnabled(true);

034 }

035

036 public int getMaxRotationAngle() {

037 return mMaxRotationAngle;

038 }

039

040 public void setMaxRotationAngle(int maxRotationAngle) {

041 mMaxRotationAngle = maxRotationAngle;

042 }

043

044 public boolean getCircleMode() {

045 return mCircleMode;

046 }

047

048 public void setCircleMode(boolean isCircle) {

049 mCircleMode = isCircle;

050 }

051

052 public boolean getAlphaMode() {

053 return mAlphaMode;

054 }

055

056 public void setAlphaMode(boolean isAlpha) {

057 mAlphaMode = isAlpha;

058 }

059

060 public int getMaxZoom() {

061 return mMaxZoom;

062 }

063

064 public void setMaxZoom(int maxZoom) {

065 mMaxZoom = maxZoom;

066 }

067

068 private int getCenterOfCoverflow() {

069 return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2

070 + getPaddingLeft();

071 }

072

073 private static int getCenterOfView(View view) {

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

075 }

076

077 protected boolean getChildStaticTransformation(View child, Transformation t) {

078 final int childCenter = getCenterOfView(child);

079 final int childWidth = child.getWidth();

080 int rotationAngle = 0;

081 t.clear();

082 t.setTransformationType(Transformation.TYPE_MATRIX);

083 if (childCenter == mCoveflowCenter) {

084 transformImageBitmap((ImageView) child, t, 0);

085 } else {

086 rotationAngle = (int) (((float) (mCoveflowCenter - childCenter) / childWidth) * mMaxRotationAngle);

087 if (Math.abs(rotationAngle) > mMaxRotationAngle) {

088 rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle

089 : mMaxRotationAngle;

090 }

091 transformImageBitmap((ImageView) child, t, rotationAngle);

092 }

093 return true;

094 }

095

096 /**

097 * 这就是所谓的在大小的布局时,这一观点已经发生了改变。如果你只是添加到视图层次,有人叫你旧的观念价值观为0。

098 *

099 * @param w

100 * Current width of this view.

101 * @param h

102 * Current height of this view.

103 * @param oldw

104 * Old width of this view.

105 * @param oldh

106 * Old height of this view.

107 */

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

109 mCoveflowCenter = getCenterOfCoverflow();

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

111 }

112

113 /**

114 * 把图像位图的角度通过

115 *

116 * @param imageView

117 * ImageView the ImageView whose bitmap we want to rotate

118 * @param t

119 * transformation

120 * @param rotationAngle

121 * the Angle by which to rotate the Bitmap

122 */

123 private void transformImageBitmap(ImageView child, Transformation t,

124 int rotationAngle) {

125 mCamera.save();

126 final Matrix imageMatrix = t.getMatrix();

127 final int imageHeight = child.getLayoutParams().height;

128 final int imageWidth = child.getLayoutParams().width;

129 final int rotation = Math.abs(rotationAngle);

130 mCamera.translate(0.0f, 0.0f, 100.0f);

131

132 // 如视图的角度更少,放大

133 if (rotation <= mMaxRotationAngle) {

134 float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));

135 mCamera.translate(0.0f, 0.0f, zoomAmount);

136 if (mCircleMode) {

137 if (rotation < 40)

138 mCamera.translate(0.0f, 155, 0.0f);

139 else

140 mCamera.translate(0.0f, (255 - rotation * 2.5f), 0.0f);

141 }

142 if (mAlphaMode) {

143 ((ImageView) (child)).setAlpha((int) (255 - rotation * 2.5));

144 }

145 }

146 mCamera.rotateY(rotationAngle);

147 mCamera.getMatrix(imageMatrix);

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

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

150 mCamera.restore();

151 }

152 }

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
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

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