探究===Gallery水平滑动效果
Android控件Gallery用处非常多，下面讲解一种选择中到的例子：
效果图如下：
下面贴一下主要关键代码：
package com.example.gaga;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Shader.TileMode;
public class BitmapUtil {
public static Bitmap createTxtImage(String txt, int txtSize) {
Bitmap mbmpTest = Bitmap.createBitmap(txt.length() * txtSize + 4,
txtSize + 4, Config.ARGB_8888);
Canvas canvasTemp = new Canvas(mbmpTest);
Paint p = new Paint();
p.setAntiAlias(true);
p.setColor(Color.RED);
p.setTextSize(txtSize);
canvasTemp.drawText(txt, 2, txtSize - 2, p);
return mbmpTest;
}
public static Bitmap createReflectedImage(Bitmap originalImage) {
// The gap we want between the reflection and the original image
final int reflectionGap = 0;
int width = originalImage.getWidth();
int height = originalImage.getHeight();
// This will not scale but will flip on the Y axis
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
// Create a Bitmap with the flip matrix applied to it.
// We only want the bottom half of the image
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
height / 2, width, height / 2, matrix, false);
// Create a new bitmap with same width but taller to fit reflection
Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
(height + height / 2), Config.ARGB_8888);
// Create a new Canvas with the bitmap that's big enough for
// the image plus gap plus reflection
Canvas canvas = new Canvas(bitmapWithReflection);
// Draw in the original image
canvas.drawBitmap(originalImage, 0, 0, null);
// Draw in the gap
Paint defaultPaint = new Paint();
canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
// Draw in the reflection
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
// Create a shader that is a linear gradient that covers the reflection
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0,
originalImage.getHeight(), 0, bitmapWithReflection.getHeight()
+ reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
// Set the paint to use this shader (linear gradient)
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.
package com.example.gaga;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.Gallery;
public class CustomGallery extends Gallery{
public CustomGallery(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
// TODO Auto-generated method stub
return false;
}
}
3.
package com.example.gaga;
public class University {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
4.
package com.example.gaga;
import java.util.ArrayList;
import android.content.Context;
import android.graphics.Point;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.Toast;
public class UniversityAdapter extends BaseAdapter {
private Context context;
private ArrayList<University> list;
public UniversityAdapter(Context context, ArrayList<University> list) {
super();
this.context = context;
this.list = list;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return Integer.MAX_VALUE;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
private int select=0;
public void notifyDataSetChanged(int all){
select=all;
super.notifyDataSetChanged();
}
@Override
public View getView(int position, View arg1, ViewGroup arg2) {
// TODO Auto-generated method stub
ImageView in=new ImageView(context);
if (select==position) {
University pro=list.get(position%list.size());
in.setImageBitmap(BitmapUtil.createReflectedImage(BitmapUtil.createTxtImage(pro.getName(), 28)));
}else {
University pro=list.get(position%list.size());
in.setImageBitmap(BitmapUtil.createTxtImage(pro.getName(), 22));
}
return in;
}
}
5.
package com.example.gaga;
import java.util.ArrayList;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
public class MainActivity extends Activity implements OnItemSelectedListener, OnItemClickListener {
private CustomGallery glllery;
private UniversityAdapter padapter;
private ArrayList<University> list=new ArrayList<University>();
private void init(){
padapter=new UniversityAdapter(MainActivity.this, list);
University p=new University();
p.setName("中国大学");
list.add(p);
University p1=new University();
p1.setName("河南大学");
list.add(p1);
University p2=new University();
p2.setName("郑州大学");
list.add(p2);
University p3=new University();
p3.setName("北京交通大学");
list.add(p3);
University p4=new University();
p4.setName("清华大学");
list.add(p4);
University p5=new University();
p5.setName("北京大学");
list.add(p5);
glllery.setAdapter(padapter);
glllery.setSelection(Integer.MAX_VALUE/2);
glllery.setOnItemSelectedListener(this);
glllery.setOnItemClickListener(this);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
glllery=(CustomGallery) this.findViewById(R.id.gagagagaga);
init();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
padapter.notifyDataSetChanged(arg2);
// Toast.makeText(MainActivity.this, ""+arg2, Toast.LENGTH_LONG).show();
//Toast.makeText(MainActivity.this, arg2, 1).show();
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO Auto-generated method stub position%list.size()
Toast.makeText(MainActivity.this, ""+list.get(arg2%list.size()).getName(), Toast.LENGTH_LONG).show();
}
}
6.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<com.example.gaga.CustomGallery
android:id="@+id/gagagagaga"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:spacing="10dp"
android:unselectedAlpha="0.5"
android:layout_marginTop="40dp"
/>
</RelativeLayout>
本应用主要是复写了Gallery的一些方法，此控件的用处非常多，本次介绍的只是一种效果。后续继续对此控件进行总结！！！