雷達掃描view,先看下整體效果:
項目地址:https://github.com/buder-cp/CustomView/blob/master/buder_DN_view/buderdn03/src/main/java/com/test/buderdn03/RadarGradientView.java
準備兩個畫筆,一個是一圈圈的圓圈,另一個是掃描畫筆;
動畫實現
這裏實現動畫的時候,用到了Matrix這個東西,也就是矩陣。上學的時候,線性代數老師講各種線性變換時,腦子裏在想,這玩意是幹嘛使得,現在總算是遇上了,現在看起來也是雲裏霧裏。總的來說就是可以使用Matrix實現強大的圖形動畫,包括位移、旋轉、縮放及透明變化等效果,matrix有着一系列的setTranslate,setRotate,setScale等方法。很方便的實現圖形各種變換,主要還是需要理解各種變換。
核心的雷達掃描動畫是利用了Matrix的Rotate函數。對Matrix有興趣的同學可以深入研究一下,這篇博客對此講的很仔細
代碼實現:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.SweepGradient;
import android.util.AttributeSet;
import android.view.View;
import androidx.annotation.Nullable;
public class RadarGradientView extends View {
private int mWidth, mHeight;
//五個圓
private float[] pots = {0.05f, 0.1f, 0.15f, 0.2f, 0.25f};
private Matrix matrix = new Matrix(); // 旋轉需要的矩陣
private Paint mPaintCircle; // 畫圓用到的paint
private Paint mPaintRadar; // 掃描用到的paint
public RadarGradientView(Context context) {
super(context);
// 畫圓用到的paint
mPaintCircle = new Paint();
mPaintCircle.setStyle(Paint.Style.STROKE); // 描邊
mPaintCircle.setStrokeWidth(3); // 寬度
mPaintCircle.setAlpha(20); // 透明度
mPaintCircle.setAntiAlias(true); // 抗鋸齒
mPaintCircle.setColor(Color.parseColor("#B0C4DE")); // 設置顏色 亮鋼蘭色
// 掃描用到的paint
mPaintRadar = new Paint();
mPaintRadar.setStyle(Paint.Style.FILL_AND_STROKE); // 填充
mPaintRadar.setAntiAlias(true); // 抗鋸齒
post(run);
}
public RadarGradientView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
public RadarGradientView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// 取屏幕的寬高是爲了把雷達放在屏幕的中間
mWidth = getMeasuredWidth();
mHeight = getMeasuredHeight();
mWidth = mHeight = Math.min(mWidth, mHeight);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int i = 0; i < pots.length; i++) {
canvas.drawCircle(mWidth / 2, mHeight / 2, mWidth * pots[i], mPaintCircle);
}
// 畫布的旋轉變換 需要調用save() 和 restore()
canvas.save();
// 掃描渲染shader
Shader scanShader = new SweepGradient(mWidth / 2, mHeight / 2,
new int[]{Color.TRANSPARENT, Color.parseColor("#84B5CA")}, null);
mPaintRadar.setShader(scanShader); // 設置着色器
canvas.concat(matrix);
canvas.drawCircle(mWidth / 2, mHeight / 2, mWidth * pots[4], mPaintRadar);
canvas.restore();
}
private Runnable run = new Runnable() {
@Override
public void run() {
int scanSpeed = 1; // 掃描速度
matrix.postRotate(scanSpeed, mWidth / 2, mHeight / 2); // 旋轉矩陣
invalidate(); // 通知view重繪
postDelayed(run, 10); // 調用自身 重複繪製
}
};
}