仿照华为手机的系统自带天气预报的UI天气数值显示部分
效果图:
橙色部分是有渐变效果，图片上不大看的出来了，上面浅一点，下面深一点。
原理其实就是花了很多条短线：根据圆心和半径来确定每条线的x,y终点坐标,以及根据圆心和(半径-短线长度)来确定每条线的x,y起点坐标，然后起点到终点画线就可以了。
主要用到点三角函数的知识：
<span style="white-space:pre"></span>/**主要用到的类也就是Canvas、Paint、Matrix、SweepGradient(扫描渐变渲染效果)
* 根据半径和角度计算x坐标
*/
private float calculateX(float r, double angle) {
angle = angle * ((2 * Math.PI) / 360);
Log.i(TAG, "angle = " + angle + ",Math.sin(angle) = " + Math.sin(angle));
double x = r * Math.sin(angle);
double xFinal = centerX + x;
return (float) xFinal;
}
/**
* 根据半径和角度计算y坐标
*/
private float calculateY(float r, double angle) {
angle = angle * ((2 * Math.PI) / 360);
Log.i(TAG, "angle = " + angle + ",Math.cos(angle) = " + Math.cos(angle));
double y = r * Math.cos(angle);
double yFinal = centerY - y;
return (float) yFinal;
}
贴上代码：
package com.cc.test.view;希望对大家有用，欢迎拍砖，欢迎指正！
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Shader;
import android.graphics.SweepGradient;
import android.graphics.Typeface;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
/**
* 线条圆圈控件(仿华为系统天气预报UI)
* @author zhangyu
* @date 2016-4-1
*/
public class LineCircle extends View {
private static final String TAG = "LineCircle";
private float centerX, centerY;
private int viewWidth, viewHeight;
private Paint linePaint;
private TextPaint whitePaint;
// 有渐变颜色的旋转起止角度
private float startAngle = 21, stopAngle = 123;
// 圆半径 线长度
private float r, l;
private Shader shader, shaderWhite;
//起止温度
private int startTem = 19,stopTem = 24;
public LineCircle(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
public LineCircle(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public LineCircle(Context context) {
super(context);
init(context);
}
private void init(Context context) {
linePaint = new Paint();
linePaint.setStrokeWidth(3);
linePaint.setAntiAlias(true);
whitePaint = new TextPaint();
whitePaint.setColor(Color.WHITE);
whitePaint.setStrokeWidth(4);
whitePaint.setAntiAlias(true);
}
/**
* 设置开始角度
* 开始与结束角度内显示为渐变彩色，反映当前温度范围.
* @param startAngle 开始角度
* @return 设置成功返回true 否则返回false
*/
public boolean setStartAngle(float startAngle){
if(startAngle >= 0 && startAngle <= 360){
this.startAngle = startAngle;
invalidate();
return true;
}else
return false;
}
/**
* 设置结束角度
* 开始与结束角度内显示为渐变彩色，反映当前温度范围.
* @param stopAngle 结束角度
* @return 设置成功返回true 否则返回false
*/
public boolean setStopAngle(float stopAngle){
if(stopAngle >= 0 && stopAngle <= 360){
this.stopAngle = stopAngle;
invalidate();
return true;
}else
return false;
}
/**
* 设置起始温度
* @param startTem
*/
public void setStartTem(int startTem){
this.startTem = startTem;
invalidate();
}
/**
* 设置截止温度
* @param stopTem
*/
public void setStopTem(int stopTem){
this.stopTem = stopTem;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
for (double angle = 0; angle <= 360d; angle += 3.0d) {
float xStart = calculateX(r, angle);
float xStop = calculateX(r - l, angle);
float yStart = calculateY(r, angle);
float yStop = calculateY(r - l, angle);
if (angle <= stopAngle && angle >= startAngle) {
linePaint.setShader(shader);
} else
linePaint.setShader(shaderWhite);
if (angle == 204 || angle == 156) {
linePaint.setStrokeWidth(2);
float xStartL = calculateX(r * 1.05f, angle);
float xStopL = calculateX((r - l), angle);
float yStartL = calculateY(r * 1.05f, angle);
float yStopL = calculateY((r - l), angle);
canvas.drawLine(xStartL, yStartL, xStopL, yStopL, linePaint);//底部两条较长的线
} else if (!(angle < 204 && angle > 156)) {
linePaint.setStrokeWidth(3);
canvas.drawLine(xStart, yStart, xStop, yStop, linePaint);//画短线
}
Log.d(TAG, "angle = " + angle + ",xStart = " + xStart + "，xStop = " + xStop + "，yStart = " + yStart + "，yStop = " + yStop);
}
drawCenterTem(canvas);
drawStartTem(canvas);
drawStopTem(canvas);
super.onDraw(canvas);
}
/**
* 根据半径和角度计算x坐标
*/
private float calculateX(float r, double angle) {
angle = angle * ((2 * Math.PI) / 360);
Log.i(TAG, "angle = " + angle + ",Math.sin(angle) = " + Math.sin(angle));
double x = r * Math.sin(angle);
double xFinal = centerX + x;
return (float) xFinal;
}
/**
* 根据半径和角度计算y坐标
*/
private float calculateY(float r, double angle) {
angle = angle * ((2 * Math.PI) / 360);
Log.i(TAG, "angle = " + angle + ",Math.cos(angle) = " + Math.cos(angle));
double y = r * Math.cos(angle);
double yFinal = centerY - y;
return (float) yFinal;
}
/**
* 画中心位置温度
*
* @param canvas
*/
private void drawCenterTem(Canvas canvas) {
whitePaint.setTextSize(r * 0.6f);
whitePaint.setTypeface(Typeface.DEFAULT);
canvas.drawText("24°", (centerX - r * 0.35f), (centerY + r * 0.3f), whitePaint);
}
/**
* 画起始温度
*/
private void drawStartTem(Canvas canvas) {
whitePaint.setTextSize(r * 0.1f);
canvas.drawText(startTem + "°", calculateX(r * 1.05f, startAngle), calculateY(r * 1.05f, startAngle), whitePaint);
}
/**
* 画截至温度
*/
private void drawStopTem(Canvas canvas) {
whitePaint.setTextSize(r * 0.1f);
canvas.drawText(stopTem + "°", calculateX(r * 1.05f, stopAngle), calculateY(r * 1.05f, stopAngle), whitePaint);
}
@Override
public void onWindowFocusChanged(boolean hasWindowFocus) {
viewWidth = getWidth();
viewHeight = getHeight();
centerX = viewWidth / 2f;
centerY = viewHeight / 2f;
r = viewWidth * 0.4f;
l = viewWidth * 0.05f;
Log.v(TAG, "centerX = " + centerX + ",centerY = " + centerY);
/* 设置渐变色 */
shader = new SweepGradient(centerX, centerY, new int[] { Color.parseColor("#FFDAB5"), Color.parseColor("#E87400") }, null);
shaderWhite = new SweepGradient(centerX, centerY, new int[] { Color.WHITE, Color.WHITE }, null);
Matrix matrix = new Matrix();
// 使用matrix改变渐变色起始位置，默认是在90度位置
matrix.setRotate(45, centerX, centerY);
shader.setLocalMatrix(matrix);
linePaint.setShader(shader);
invalidate();
super.onWindowFocusChanged(hasWindowFocus);
}
}