androidgraphics
㈠ android设置控件样式（边框颜色，圆角）和图片样式（圆角）
本文链接：https://blog.csdn.net/weixin_37577039/article/details/79090433
```
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="@color/colorAccent" />
<!-- 这里是设置为四周 也可以单独设置某个位置为圆角-->
<corners android:topLeftRadius="5dp"
android:topRightRadius="5dp"
android:bottomRightRadius="5dp"
android:bottomLeftRadius="5dp"/>
<stroke android:width="1dp" android:color="#000000" />
</shape
```
```
<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<!-- 边框颜色值 -->
<item>
<shape>
<solid android:color="#3bbaff" />
</shape>
</item>
<!--这个是按钮边框设置为四周 并且宽度为1-->
<item
android:right="1dp"
android:left="1dp"
android:top="1dp"
android:bottom="1dp">
<shape>
<!--这个是背景颜色-->
<solid android:color="#ffffff" />
<!--这个是按钮中的字体与按钮内的四周边距-->
<padding android:bottom="10dp"
android:left="10dp"
android:right="10dp"
android:top="10dp" />
</shape>
</item>
</layer-list>
```
使用：
```android:background="@drawable/button_edge"```
```
<?xml version="1.0" encoding="UTF-8"?>
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<!-- 填充的颜色 -->
<solid android:color="#FFFFFF" />
<!-- android:radius 弧形的半径 -->
<!-- 设置按钮的四个角为弧形 -->
<corners
android:radius="5dip" />
<!--也可单独设置-->
<!-- <corners -->
<!-- android:topLeftRadius="10dp"-->
<!-- android:topRightRadius="10dp"-->
<!-- android:bottomRightRadius="10dp"-->
<!-- android:bottomLeftRadius="10dp"-->
<!-- /> -->
**设置文字padding**
<!-- padding：Button里面的文字与Button边界的间隔 -->
<padding
android:left="10dp"
android:top="10dp"
android:right="10dp"
android:bottom="10dp"
/>
</shape>
```
```
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#FFFFFF" />
<corners android:topLeftRadius="10dp"
android:topRightRadius="10dp"
android:bottomRightRadius="10dp"
android:bottomLeftRadius="10dp"/>
</shape>
```
使用：
```
android:background="@drawable/image_circle"
```
```
Glide.with(MainActivity.this).load(croppedUri)
.transform(new GlideRectRound(MainActivity.this,6)).into(headIcon);
```
```
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.Log;
import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.BitmapTransformation;
/**
* Created by SiHao on 2018/3/3.
* Glide 的 圆角 图片 工具类
*/
public class GlideRectRound extends BitmapTransformation {
private static float radius = 0f;
// 构造方法1 无传入圆角度数 设置默认值为5
public GlideRectRound(Context context) {
this(context, 5);
}
// 构造方法2 传入圆角度数
public GlideRectRound(Context context, int dp) {
super(context);
// 设置圆角度数
radius = Resources.getSystem().getDisplayMetrics().density * dp;
}
// 重写该方法 返回修改后的Bitmap
@Override
protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
return rectRoundCrop(pool,toTransform);
}
@Override
public String getId() {
Log.e("getID",getClass().getName() + Math.round(radius));
return getClass().getName() + Math.round(radius); // 四舍五入
}
private Bitmap rectRoundCrop(BitmapPool pool, Bitmap source){
if (source == null) return null;
Bitmap result = pool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888); // ARGB_4444——代表4x4位ARGB位图,ARGB_8888——代表4x8位ARGB位图
if (result == null) {
result = Bitmap.createBitmap(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);
}
Canvas canvas = new Canvas(result);
Paint paint = new Paint();
// setShader 对图像进行渲染
// 子类之一 BitmapShader设置Bitmap的变换 TileMode 有CLAMP （取bitmap边缘的最后一个像素进行扩展），REPEAT（水平地重复整张bitmap）
//MIRROR(和REPEAT类似，但是每次重复的时候，将bitmap进行翻转)
paint.setShader(new BitmapShader(source, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP));
paint.setAntiAlias(true); // 抗锯齿
RectF rectF = new RectF(0f, 0f, source.getWidth(), source.getHeight());
canvas.drawRoundRect(rectF, radius, radius, paint);
return result;
}
}
```
圆角：
```
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;
import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.BitmapTransformation;
/**
* Created by SiHao on 2018/3/3.
* Glide圆形图片工具类
*/
public class GlideCircleBitmap extends BitmapTransformation{
public GlideCircleBitmap(Context context) {
super(context);
}
// 重写该方法 返回修改后的Bitmap
@Override
protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
return circleCrop(pool, toTransform);
}
@Override
public String getId() {
return getClass().getName();
}
private static Bitmap circleCrop(BitmapPool pool, Bitmap source) {
if (source == null) return null;
// 边长取长宽最小值
int size = Math.min(source.getWidth(), source.getHeight());
int x = (source.getWidth() - size) / 2;
int y = (source.getHeight() - size) / 2;
// TODO this could be acquired from the pool too
Bitmap squared = Bitmap.createBitmap(source, x, y, size, size);
Bitmap result = pool.get(size, size, Bitmap.Config.ARGB_8888);// ARGB_4444——代表4x4位ARGB位图,ARGB_8888——代表4x8位ARGB位图
if (result == null) {
result = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
}
Canvas canvas = new Canvas(result);
Paint paint = new Paint();
// setShader 对图像进行渲染
// 子类之一 BitmapShader设置Bitmap的变换 TileMode 有CLAMP （取bitmap边缘的最后一个像素进行扩展），REPEAT（水平地重复整张bitmap）
//MIRROR(和REPEAT类似，但是每次重复的时候，将bitmap进行翻转)
paint.setShader(new BitmapShader(squared, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP));
paint.setAntiAlias(true);// 抗锯齿
// 半径取 size的一半
float r = size / 2f;
canvas.drawCircle(r, r, r, paint);
return result;
}
}
```
```
URL url = new URL(String类型的字符串); //将String类型的字符串转换为URL格式
holder.UserImage.setImageBitmap(BitmapFactory.decodeStream(url.openStream()));
```
```
//得到资源文件的BitMap
Bitmap image= BitmapFactory.decodeResource(getResources(),R.drawable.dog);
//创建RoundedBitmapDrawable对象
RoundedBitmapDrawable roundImg =RoundedBitmapDrawableFactory.create(getResources(),image);
//抗锯齿
roundImg.setAntiAlias(true);
//设置圆角半径
roundImg.setCornerRadius(30);
//设置显示图片
imageView.setImageDrawable(roundImg);
```
```
//如果是圆的时候，我们应该把bitmap图片进行剪切成正方形， 然后再设置圆角半径为正方形边长的一半即可
Bitmap image = BitmapFactory.decodeResource(getResources(), R.drawable.dog);
Bitmap bitmap = null;
//将长方形图片裁剪成正方形图片
if (image.getWidth() == image.getHeight()) {
bitmap = Bitmap.createBitmap(image, image.getWidth() / 2 - image.getHeight() / 2, 0, image.getHeight(), image.getHeight());
} else {
bitmap = Bitmap.createBitmap(image, 0, image.getHeight() / 2 - image.getWidth() / 2, image.getWidth(), image.getWidth());
}
RoundedBitmapDrawable roundedBitmapDrawable = RoundedBitmapDrawableFactory.create(getResources(), bitmap);
//圆角半径为正方形边长的一半
roundedBitmapDrawable.setCornerRadius(bitmap.getWidth() / 2);
//抗锯齿
roundedBitmapDrawable.setAntiAlias(true);
imageView.setImageDrawable(roundedBitmapDrawable);
```
㈡ Android如何纯java代码实现字体阴影效果
Android实现纯java代码字体阴影效果，主要是通过activity的draw方法，进行重新绘制，如下代码：
packagecanvas.test;
importandroid.app.Activity;
importandroid.os.Bundle;
importandroid.content.Context;
importandroid.graphics.Bitmap;
importandroid.graphics.BitmapFactory;
importandroid.graphics.Canvas;
importandroid.graphics.Color;
importandroid.graphics.Paint;
importandroid.graphics.PorterDuff;
importandroid.graphics.PorterDuff.Mode;
importandroid.graphics.PorterDuffXfermode;
importandroid.graphics.Rect;
importandroid.graphics.RectF;
importandroid.graphics.drawable.Drawable;
importandroid.view.View;
{
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(newImageEffect(this));
}
classImageEffectextendsView{
Paintpaint;
publicImageEffect(Contextcontext){
super(context);
paint=newPaint();//初始化画笔，为后面阴影效果使用。
paint.setAntiAlias(true);//去除锯齿。
paint.setShadowLayer(5f,5.0f,5.0f,Color.BLACK);//设置阴影层，这是关键。
paint.setXfermode(newPorterDuffXfermode(Mode.SRC_IN));
}
@Override
publicvoidonDraw(Canvascanvas){
super.onDraw(canvas);
intposX=20;
intposY=50;
intPicWidth,PicHegiht;
Drawabledrawable=getResources().getDrawable(R.drawable.button);
Drawabledbe=getResources().getDrawable(R.drawable.button).mutate();//如果不调用mutate方法，则原图也会被改变，因为调用的资源是同一个，所有对象是共享状态的。
DrawabledrawTest=getResources().getDrawable(R.drawable.button);
Bitmapbmp=BitmapFactory.decodeResource(getResources(),R.drawable.button);
PicWidth=drawable.getIntrinsicWidth();
PicHegiht=drawable.getIntrinsicHeight();
drawTest.setBounds(posX,(2*posY)+PicHegiht,posX+PicWidth,(2*posY)+2*PicHegiht);
drawable.setBounds(posX,posY,posX+PicWidth,posY+PicHegiht);
dbe.setBounds(0,0,PicWidth,PicHegiht);
canvas.drawColor(Color.WHITE);//设置画布颜色
canvas.save(Canvas.MATRIX_SAVE_FLAG);
dbe.setColorFilter(0x7f000000,PorterDuff.Mode.SRC_IN);
canvas.translate(posX+(int)(0.9*PicWidth/2),posY+PicHegiht/2);//图像平移为了刚好在原图后形成影子效果。
canvas.skew(-0.9F,0.0F);//图像倾斜效果。
canvas.scale(1.0f,0.5f);//图像（其实是画布）缩放，Y方向缩小为1/2。
dbe.draw(canvas);//此处为画原图像影子效果图，比原图先画，则会在下层。
drawable.clearColorFilter();
canvas.restore();
canvas.save(Canvas.MATRIX_SAVE_FLAG);
drawable.draw(canvas);//此处为画原图像，由于canvas有层次效果，因此会盖在影子之上。
canvas.restore();
//默认无效果原图
canvas.save(Canvas.MATRIX_SAVE_FLAG);
drawTest.draw(canvas);
canvas.restore();
//图片阴影效果
canvas.save(Canvas.MATRIX_SAVE_FLAG);
//Rectrect=newRect(2*posX+PicWidth,2*posY+PicHegiht,2*posX+2*PicWidth,2*posY+2*PicHegiht);//此为理论上的阴影图坐标
Rectrect=newRect(2*posX+PicWidth+3,2*posY+PicHegiht+3,2*posX+2*PicWidth-2,2*posY+2*PicHegiht-2);
//由于图片的实际尺寸比显示出来的图像要大一些，因此需要适当更改下大小，以达到较好的效果
RectFrectF=newRectF(rect);
canvas.drawRoundRect(rectF,10f,10f,paint);//在原有矩形基础上，画成圆角矩形，同时带有阴影层。
canvas.drawBitmap(bmp,2*posX+PicWidth,2*posY+PicHegiht,null);//画上原图。
canvas.restore();
}
}
}
㈢ java.io.NotSerializableException: android.graphics.Paint
应该是没有序列化。序列化可以将内存中的类写入文件或数据库中。比如user类。序列化代码：public class UserInfo implements Serializable { }
tomcat停止时，session要将对象信息序列化到硬盘，tomcat重启时，再反序列化到session中。这个异常还是我说的那个你没有把你的类序列化。只要在你的类名后加上implements Serializable就行了。
㈣ 在Android中要实现图表统计该怎么做
package com.yzxy.draw;
import java.util.ArrayList;
import java.util.HashMap;
import com.yzxy.draw.tools.Tools;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.graphics.RectF;
import android.graphics.Paint.Style;
import android.graphics.Typeface;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
@SuppressLint("ViewConstructor")
class MyTuView extends View{
public static final int RECT_SIZE = 10;
private Point mSelectedPoint = null;
public static enum Mstyle
{
Line,scroll
}
private Mstyle mstyle=Mstyle.Line;
private Point[] mPoints = new Point[8];
Context context;
Activity act;
int bheight=0;
Tools tool=new Tools();
HashMap map;
ArrayList dlk;
int totalvalue=30;
int pjvalue=5;
String xstr,ystr;
int margint=15;
int marginb=40;
int c=0;
int resid=0;
Boolean isylineshow;
public MyTuView(Context context,HashMap map,int totalvalue,int pjvalue,String xstr,String ystr,Boolean isylineshow)
{
super(context);
this.context=context;
this.act = (Activity)context;
this.map=map;
this.totalvalue=totalvalue;
this.pjvalue=pjvalue;
this.xstr=xstr;
this.ystr=ystr;
this.isylineshow=isylineshow;
act.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
@SuppressLint("DrawAllocation")
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// canvas.drawColor(Color.GRAY);
if(c!=0)
this.setbg(c);
if(resid!=0)
this.setBackgroundResource(resid);
dlk=tool.getintfrommap(map);
int height=getHeight();
if(bheight==0)
bheight=height-marginb;
int width=getWidth();
Log.i("w", getWidth()+":"+getHeight());
int blwidh=tool.dip2px(context,50);
int pjsize=totalvalue/pjvalue;
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.GRAY);
paint.setStrokeWidth(1);
paint.setStyle(Style.STROKE);
// 画直线(横向)
for(int i=0;i xlist=new ArrayList();//记录每个x的值
//画直线（纵向）
for(int i=0;i dlk,HashMap map,ArrayList xlist,int max,int h)
{
Point[] points=new Point[dlk.size()];
for(int i=0;i getMap() {
return map;
}
public void setMap(HashMap map) {
this.map = map;
}
public int getTotalvalue() {
return totalvalue;
}
public void setTotalvalue(int totalvalue) {
this.totalvalue = totalvalue;
}
public int getPjvalue() {
return pjvalue;
}
public void setPjvalue(int pjvalue) {
this.pjvalue = pjvalue;
}
public String getXstr() {
return xstr;
}
public void setXstr(String xstr) {
this.xstr = xstr;
}
public String getYstr() {
return ystr;
}
public void setYstr(String ystr) {
this.ystr = ystr;
}
public int getMargint() {
return margint;
}
public void setMargint(int margint) {
this.margint = margint;
}
public Boolean getIsylineshow() {
return isylineshow;
}
public void setIsylineshow(Boolean isylineshow) {
this.isylineshow = isylineshow;
}
public int getMarginb() {
return marginb;
}
public void setMarginb(int marginb) {
this.marginb = marginb;
}
public Mstyle getMstyle() {
return mstyle;
}
public void setMstyle(Mstyle mstyle) {
this.mstyle = mstyle;
}
public int getBheight() {
return bheight;
}
public void setBheight(int bheight) {
this.bheight = bheight;
}
public int getC() {
return c;
}
public void setC(int c) {
this.c = c;
}
public int getResid() {
return resid;
}
public void setResid(int resid) {
this.resid = resid;
}
}
代码片段
package com.yzxy.draw.tools;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Environment;
public class Tools
{
private final static String ALBUM_PATH = Environment.getExternalStorageDirectory() + "/yueqiu/";
public int dip2px(Context context, float dpValue)
{
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
public int px2dip(Context context, float pxValue)
{
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (pxValue / scale + 0.5f);
}
public ArrayList getintfrommap(HashMap map)
{
ArrayList dlk=new ArrayList();
int position=0;
@SuppressWarnings("rawtypes")
Set set= map.entrySet();
@SuppressWarnings("rawtypes")
Iterator iterator = set.iterator();
while(iterator.hasNext())
{
@SuppressWarnings("rawtypes")
Map.Entry mapentry = (Map.Entry)iterator.next();
dlk.add((Double)mapentry.getKey());
}
for(int i=0;i
代码片段
package com.yzxy.draw;
import java.io.IOException;
import java.util.HashMap;
import com.yzxy.draw.MyTuView.Mstyle;
import com.yzxy.draw.tools.Tools;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.RelativeLayout;
import android.widget.RelativeLayout.LayoutParams;
import android.widget.Toast;
import android.app.Activity;
import android.content.res.XmlResourceParser;
import android.graphics.Bitmap;
import android.graphics.Color;
public class MainActivity extends Activity {
MyTuView tu;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
HashMap map=new HashMap();
map.put(1.0, 8.0);
map.put(7.0, 130.0);
map.put(2.0, 4.0);
map.put(3.0, 1.0);
map.put(4.0, 18.0);
map.put(5.0, 160.0);
map.put(6.0, 180.0);
map.put(8.1, 133.5);
tu=new MyTuView(this,map,200,50,"x","y",false);
// tu.setC(Color.CYAN);
tu.setResid(R.drawable.bg);
// tu.setBheight(200);
tu.setTotalvalue(200);
tu.setPjvalue(50);
tu.setXstr("x");
tu.setYstr("y");
tu.setMargint(20);
tu.setBackgroundColor(Color.WHITE);
tu.setMarginb(50);
tu.setMstyle(Mstyle.scroll);
RelativeLayout rela=getlayout(R.layout.activity_main);
rela.addView(tu);
LayoutParams parm=new LayoutParams(1200,400);
parm.setMargins(50, 50, 50, 100);
tu.setLayoutParams(parm);
setContentView(rela);
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
// TODO Auto-generated method stub
if(item.getItemId() == R.id.menu_settings)
{
if (false == tu.isDrawingCacheEnabled())
{
tu.setDrawingCacheEnabled(true);
}
Bitmap bitmap = tu.getDrawingCache();
Tools tool=new Tools();
try {
Boolean b=tool.saveFile(bitmap, "aaaa.png");
if(b)
Toast.makeText(this, "success", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(item.getItemId() == R.id.menu_ch)
{
HashMap map=new HashMap();
map.put(1.0, 21.0);
map.put(3.0, 25.0);
map.put(4.0, 32.0);
map.put(5.0, 31.0);
map.put(6.0, 26.0);
tu.setTotalvalue(40);
tu.setPjvalue(10);
tu.setMap(map);
tu.setIsylineshow(true);
tu.postInvalidate();
}
if(item.getItemId() == R.id.menu_ch2)
{
HashMap map=new HashMap();
map.put(1.0, 41.0);
map.put(3.0, 25.0);
map.put(4.0, 32.0);
map.put(5.0, 41.0);
map.put(6.0, 16.0);
map.put(7.0, 36.0);
map.put(8.0, 26.0);
tu.setTotalvalue(50);
tu.setPjvalue(10);
tu.setMap(map);
tu.setMstyle(Mstyle.Line);
tu.setIsylineshow(false);
tu.postInvalidate();
}
return true;
}
public RelativeLayout getlayout(int r)
{
LayoutInflater inflater = (LayoutInflater)getSystemService(android.content.Context.LAYOUT_INFLATER_SERVICE );
try {
XmlResourceParser parser = getResources().getLayout(r);
RelativeLayout layout = (RelativeLayout) inflater.inflate(parser, null);
return layout;
}catch (Exception e) {
// TODO: handle exception
}
return null;
}
}
㈤ android 怎么画2层圆环
Android绘制两层圆环，可以使用自定义View，继承View，重写里面的Ondraw方法，花两个同心圆，示例如下：
packagecom.cn.myvn;
importandroid.content.Context;
importandroid.graphics.Canvas;
importandroid.graphics.Paint;
importandroid.util.AttributeSet;
importandroid.view.View;
{
privatefinalPaintpaint;
privatefinalContextcontext;
publicRingView(Contextcontext){
//TODOAuto-generatedconstructorstub
this(context,null);
}
publicRingView(Contextcontext,AttributeSetattrs){
super(context,attrs);
//TODOAuto-generatedconstructorstub
this.context=context;
this.paint=newPaint();
this.paint.setAntiAlias(true);//消除锯齿
this.paint.setStyle(Paint.Style.STROKE);//绘制空心圆
}
@Override
protectedvoidonDraw(Canvascanvas){
//TODOAuto-generatedmethodstub
intcenter=getWidth()/2;
intinnerCircle=dip2px(context,83);//设置内圆半径
intringWidth=dip2px(context,5);//设置圆环宽度
//绘制内圆
this.paint.setARGB(155,167,190,206);
this.paint.setStrokeWidth(2);
canvas.drawCircle(center,center,innerCircle,this.paint);
//绘制圆环
this.paint.setARGB(255,212,225,233);
this.paint.setStrokeWidth(ringWidth);
canvas.drawCircle(center,center,innerCircle+1+ringWidth/2,this.paint);
//绘制外圆
this.paint.setARGB(155,167,190,206);
this.paint.setStrokeWidth(2);
canvas.drawCircle(center,center,innerCircle+ringWidth,this.paint);
super.onDraw(canvas);
}
}
㈥ android怎么用paint实现图像的渐变出现
在android.graphics中提供了有关Gradient字样的类，例如LinearGradient线性渐变、 RadialGradient径向渐变和SweepGradient角度渐变三种，他们的基类为android.graphics.Shader。为了演 示图像渐变效果，下面给出一个简单的实例。
一、LinearGradient线性渐变
在android平台中提供了两种重载方式来实例化该类分别为，他们的不同之处为参数中第一种方法可以用颜色数组，和位置来实现更细腻的过渡效果， 比如颜 色采样int[] colors数组中存放20种颜色，则渐变将会逐一处理。而第二种方法参数仅为起初颜色color0和最终颜色color1。
LinearGradient(float x0, float y0, float x1, float y1, int[] colors, float[] positions, Shader.TileMode tile)
LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1, Shader.TileMode tile)
使用实例如下：
Paint p=new Paint();
LinearGradient lg=new LinearGradient(0,0,100,100,Color.RED,Color.BLUE,Shader.TileMode.MIRROR); //参数一为渐变起初点坐标x位置，参数二为y轴位置，参数三和四分辨对应渐变终点，最后参数为平铺方式，这里设置为镜像
刚才已经讲到Gradient是基于Shader类，所以我们通过Paint的setShader方法来设置这个渐变，代码如下：
p.setShader(lg);
canvas.drawCicle(0,0,200,p); //参数3为画圆的半径，类型为float型。
二、RadialGradient镜像渐变
有了上面的基础，我们一起来了解下径向渐变。和上面参数唯一不同的是，径向渐变第三个参数是半径，其他的和线性渐变相同。
RadialGradient(float x, float y, float radius, int[] colors, float[] positions, Shader.TileMode tile)
RadialGradient(float x, float y, float radius, int color0, int color1, Shader.TileMode tile)
三、SweepGradient角度渐变
对于一些3D立体效果的渐变可以尝试用角度渐变来完成一个圆锥形，相对来说比上面更简单，前两个参数为中心点，然后通过载入的颜色来平均的渐变渲染。
SweepGradient(float cx, float cy, int[] colors, float[] positions) //对于最后一个参数SDK上的描述为May be NULL. The relative position of each corresponding color in the colors array, beginning with 0 and ending with 1.0. If the values are not monotonic, the drawing may proce unexpected results. If positions is NULL, then the colors are automatically spaced evenly.，所以建议使用下面的重载方法，本方法一般为NULL即可。
SweepGradient(float cx, float cy, int color0, int color1)
到此，希望大家对图像特效处理有了一定的认识，了解这些对打好Android游戏开发的基础很有好处。
转载