Android 颜色渲染(五) LinearGradient线性渲染

Android 颜色处理(三) LinearGradient线性渲染

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:

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;

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); 
	}

}