Android 颜色渲染(五) LinearGradient线性渲染

转自：http://blog.csdn.net/t12x3456/article/details/10566219

Android 颜色处理(五) LinearGradient线性渲染

相信很多人都看过歌词同步的效果, 一是竖直方向的滚动，另一方面是水平方面的歌词颜色渐变点亮效果,这种效果怎么做呢? 这就需要用到LinearGradient线性渲染,下面还是先看具体的使用:



LinearGradient有两个构造函数;

public LinearGradient(float x0, float y0, float x1, float y1, int[] colors, float[] positions,Shader.TileMode tile)

参数:

float x0: 渐变起始点x坐标

float y0:渐变起始点y坐标



float x1:渐变结束点x坐标



float y1:渐变结束点y坐标



int[] colors:颜色 的int 数组



float[] positions: 相对位置的颜色数组,可为null, 若为null,可为null,颜色沿渐变线均匀分布



Shader.TileMode tile: 渲染器平铺模式

public LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1,Shader.TileMode tile)

float x0: 渐变起始点x坐标

float y0:渐变起始点y坐标

float x1:渐变结束点x坐标

float y1:渐变结束点y坐标

int color0: 起始渐变色

int color1: 结束渐变色

Shader.TileMode tile: 渲染器平铺模式

效果图:



然后看一下具体怎么实现这种效果;

MainActivity:

[java] view
plain copy

package com.tony.shader;

import android.os.Bundle;

import android.app.Activity;

public class MainActivity extends Activity {

private LinearGradientView linearGradientView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

linearGradientView = new LinearGradientView(this);

setContentView(linearGradientView);

}

}

LinearGradientView;

[java] view
plain copy

package com.tony.shader;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.LinearGradient;

import android.graphics.Paint;

import android.util.AttributeSet;

import android.graphics.Shader;

import android.view.View;

public class LinearGradientView extends View {

private LinearGradient linearGradient = null;

private Paint paint = null;

public LinearGradientView(Context context)

{

super(context);

linearGradient = new LinearGradient(0, 0, 100, 100, new int[] {

Color.YELLOW, Color.GREEN, Color.TRANSPARENT, Color.WHITE }, null,

Shader.TileMode.REPEAT);

paint = new Paint();

}

public LinearGradientView(Context context, AttributeSet attrs) {

super(context, attrs);

}

@Override

protected void onDraw(Canvas canvas) {

// TODO Auto-generated method stub

super.onDraw(canvas);

//设置渲染器

paint.setShader(linearGradient);

//绘制圆环

canvas.drawCircle(240, 360, 200, paint);

}

}