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矢印を描くにはどうすればよいですか（Androidの場合）？

私はAndroidにかなり慣れておらず、Canvasをいじっています。矢印を描画しようとしていますが、シャフトを描画するだけで運が良かったので、矢印が機能していません。 。

少し検索して、Javaの例を見つけましたが、AndroidにはGeneralPathまたはAffineTransformがありません。

今のところ、私のコードは次のようになっています（矢じりは矢じりのようには見えません）：

public class DrawableView extends View {
    Context mContext;
    private int centerX;
    private int centerY;
    private int radius;
    private double arrLength;
    private double arrHeading;
    private int margin = 10;

    public DrawableView(Context context) {
        super(context);
        mContext = context;
    }


    @Override
    protected void onDraw(Canvas canvas) {
        //Paint Background
        Paint background = new Paint();
        background.setColor(getResources().getColor(R.color.background);
        canvas.drawRect(0, 0, getWidth(), getHeight(), background);

        //Set vars for Arrow Paint
        Paint paint = new Paint();
        Paint.setColor(getResources().getColor(R.color.arrowColor);
        centerX = getWidth() / 2;
        centerY = getHeight() / 2;
        arrLength = radius - 10;

        if(centerX < centerY)
            radius = centerX - margin;
        else 
            radius = centerY - margin;

        //Draw Shaft
        int[] xy = findArrowPos(arrLength, arrHeading);
        canvas.drawLine(centerX, centerY, xy[0], xy[1], Paint);

        //Draw ArrowHead
            //This is where I'm confused

    }

    private int[] findArrowPos(double length, double angle) {
        int[] points = new int[2];
        double theta = Math.toRadians(angle);
        points[0] = centerX + (int) (length * Math.cos(theta));
        points[1] = centerY + (int) (length * Math.sin(theta));
        return points;
    }
}

ガイダンスとして、次のスレッドを確認しました。
* http://www.Java-forums.org/awt-swing/6241-how-u-rotate-arrow-mark-line-moves-accordingly.html
* Javaで有向矢印線を描画する方法は？

javaandroiddrawshape
20
StartingGroovy

「PathmyPath = newPath（）;」を使用するのはどうですか。ここで、xとyの位置を指定して、線を使用して三角形を作成し、それを塗りつぶします。あなたはそれについて読むことができます、これは私がどこかから取った例です。

// create and draw triangles
// use a Path object to store the 3 line segments
// use .offset to draw in many locations
// note: this triangle is not centered at 0,0
Paint.setStyle(Paint.Style.STROKE);
Paint.setStrokeWidth(2);
Paint.setColor(Color.RED);
Path path = new Path();
path.moveTo(0, -10);
path.lineTo(5, 0);
path.lineTo(-5, 0);
path.close();
path.offset(10, 40);
canvas.drawPath(path, Paint);
path.offset(50, 100);
canvas.drawPath(path, Paint);
// offset is cumlative
// next draw displaces 50,100 from previous
path.offset(50, 100);
canvas.drawPath(path, Paint);
19
user710502

私はそれが完全に機能しているこのコードを試します：

switch (event.getAction())
{
   case MotionEvent.ACTION_DOWN:
        mPath.reset();
        mPath.moveTo(x, y);
        mX = x;
        mY = y;
        startPoint = new PointF(event.getX(), event.getY());
        endPoint = new PointF();
        invalidate();
        break;
    case MotionEvent.ACTION_MOVE:
            float dx = Math.abs(x - mX);
        System.out.println("action move");
        float dy = Math.abs(y - mY);
        if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE)
        {
        //  currentDrawingPath.path.quadTo(mX,mY,(x + mX)/2, (y + mY)/2);
        }
        mX = x;
        mY = y;
          endPoint.x = event.getX();
          endPoint.y = event.getY();
          isDrawing = true;
          invalidate();
        break;
    case MotionEvent.ACTION_UP:
           mPath.lineTo(mX, mY);
           float deltaX =   endPoint.x-startPoint.x;
           float deltaY =   endPoint.y-startPoint.y;
           float frac = (float) 0.1;
     float point_x_1 = startPoint.x + (float) ((1 - frac) * deltaX + frac * deltaY);
     float point_y_1 = startPoint.y + (float) ((1 - frac) * deltaY - frac * deltaX);
           float point_x_2 = endPoint.x;
           float point_y_2 = endPoint.y;
     float point_x_3 = startPoint.x + (float) ((1 - frac) * deltaX - frac * deltaY);
     float point_y_3 = startPoint.y + (float) ((1 - frac) * deltaY + frac * deltaX);
           mPath.moveTo(point_x_1, point_y_1);
           mPath.lineTo(point_x_2, point_y_2);
           mPath.lineTo(point_x_3, point_y_3);
           mPath.lineTo(point_x_1, point_y_1);
           mPath.lineTo(point_x_1, point_y_1);
            mCanvas.drawPath(mPath, ppaint);
            endPoint.x = event.getX();
            endPoint.y = event.getY();
            isDrawing = false;
            invalidate();
        break;
    default:
        break;
}
6
Kevin Rameshwaran

私の矢印描画コード、多分それは誰かのためにいくらか役に立つかもしれません：

    /**
 * Draw an arrow
 * change internal radius and angle to change appearance
 * - angle : angle in degrees of the arrows legs
 * - radius : length of the arrows legs
 * @author Steven Roelants 2017
 *
 * @param Paint
 * @param canvas
 * @param from_x
 * @param from_y
 * @param to_x
 * @param to_y
 */
private void drawArrow(Paint paint, Canvas canvas, float from_x, float from_y, float to_x, float to_y)
{
    float angle,anglerad, radius, lineangle;

    //values to change for other appearance *CHANGE THESE FOR OTHER SIZE ARROWHEADS*
    radius=10;
    angle=15;

    //some angle calculations
    anglerad= (float) (PI*angle/180.0f);
    lineangle= (float) (atan2(to_y-from_y,to_x-from_x));

    //tha line
    canvas.drawLine(from_x,from_y,to_x,to_y,Paint);

    //tha triangle
    Path path = new Path();
    path.setFillType(Path.FillType.EVEN_ODD);
    path.moveTo(to_x, to_y);
    path.lineTo((float)(to_x-radius*cos(lineangle - (anglerad / 2.0))),
            (float)(to_y-radius*sin(lineangle - (anglerad / 2.0))));
    path.lineTo((float)(to_x-radius*cos(lineangle + (anglerad / 2.0))),
            (float)(to_y-radius*sin(lineangle + (anglerad / 2.0))));
    path.close();

    canvas.drawPath(path, Paint);
}
4
steven roelants

私は同じ問題を抱えています。特定の方向を指す矢印が必要です。描画アルゴリズムを試してみた後、最も簡単な方法はビットマップを使用し、マトリックスを使用して回転させることであると判断しました。

ImageView image = (ImageView) findViewById(R.id.bitmap_image);
Bitmap bMap = BitmapFactory.decodeResource(getResources(), R.drawable.test);
Matrix mat = new Matrix();
mat.postRotate(90);
Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0, bMap.getWidth(), bMap.getHeight(), mat, true);
image.setImageBitmap(bMapRotate);

次に、ビットマップは、好きなように見える任意の矢印にすることができます。

3
daveD

固定長の見出しで、1秒間に数千の矢印を描画するソリューションを探している場合は、次の機能を試してください（矢印の頭のみを描画します）。

private void fillArrow(Paint paint, Canvas canvas, float x0, float y0, float x1, float y1) {
    Paint.setStyle(Paint.Style.STROKE);

    int arrowHeadLenght = 10;
    int arrowHeadAngle = 45;
    float[] linePts = new float[] {x1 - arrowHeadLenght, y1, x1, y1};
    float[] linePts2 = new float[] {x1, y1, x1, y1 + arrowHeadLenght};
    Matrix rotateMat = new Matrix();

    //get the center of the line
    float centerX = x1;
    float centerY = y1;

    //set the angle
    double angle = Math.atan2(y1 - y0, x1 - x0) * 180 / Math.PI + arrowHeadAngle;

    //rotate the matrix around the center
    rotateMat.setRotate((float) angle, centerX, centerY);
    rotateMat.mapPoints(linePts);
    rotateMat.mapPoints(linePts2);

    canvas.drawLine(linePts [0], linePts [1], linePts [2], linePts [3], Paint);
    canvas.drawLine(linePts2 [0], linePts2 [1], linePts2 [2], linePts2 [3], Paint);
}

に基づく https://gamedev.stackexchange.com/questions/44456/drawing-lines-on-Android-with-matrix

3
Alex

以下のように Path を使用し、それに応じて座標を調整します。

// Construct a wedge-shaped path
Path mPath = new Path();
mPath.moveTo(0, -50);
mPath.lineTo(-20, 60);
mPath.lineTo(0, 50);
mPath.lineTo(20, 60);
mPath.close();
2
Femi

これは、キャンバスに線を描きながら矢印を描くのに最適なコードです。

package com.example.canvasexample;

import Android.content.Context;
import Android.graphics.Canvas;
import Android.graphics.Color;
import Android.graphics.Matrix;
import Android.graphics.Paint;
import Android.graphics.Path;
import Android.support.annotation.NonNull;
import Android.util.AttributeSet;
import Android.util.Log;
import Android.view.MotionEvent;
import Android.view.View;

import Java.util.ArrayList;

import static Android.view.MotionEvent.ACTION_DOWN;
import static Android.view.MotionEvent.ACTION_MOVE;
import static Android.view.MotionEvent.ACTION_UP;

public class DrawerViewArrow extends View {
    private ArrayList<Path> drawingLinePath;
    private ArrayList<Path> drawingArrowPath;
    private ArrayList<Paint> drawingLinePaint;
    private int pathIndex = 0;
    private float startX = -1, startY = -1;
    private float mX = -1, mY = -1;

    public int arrowLength = 80;
    public int arrowWidth = 45;
    public int strokeWidth = 10;

    public DrawerViewArrow(Context context) {
        super(context);
        initPath();
    }

    public DrawerViewArrow(Context context, @NonNull AttributeSet attrs) {
        super(context, attrs);
        initPath();
    }

    public DrawerViewArrow(Context context, @NonNull AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initPath();
    }

    private Paint initPaint() {
        Paint mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(Color.GREEN);
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(strokeWidth);
        return mPaint;
    }

    private void initPath() {
        drawingLinePath = new ArrayList<>();
        drawingArrowPath = new ArrayList<>();
        drawingLinePath.add(new Path());
        drawingArrowPath.add(new Path());
        drawingLinePaint = new ArrayList<>();
        drawingLinePaint.add(initPaint());
        pathIndex++;
    }

    private Path createPath(MotionEvent event) {
        Path path = new Path();
        path.moveTo(event.getX(), event.getY());
        return path;
    }

    private void updateIndex(MotionEvent event) {
        if (pathIndex == drawingLinePath.size()) {
            drawingLinePath.add(createPath(event));
            drawingArrowPath.add(createPath(event));
            drawingLinePaint.add(initPaint());
            pathIndex++;
        }
    }


    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        if (startX > -1 && mX > -1) {
            canvas.drawLine(startX, startY, mX, mY, initPaint());
            drawArrow(canvas);
        }

        for (int index = 0; index < pathIndex; index++) {
            Path path = drawingLinePath.get(index);
            Path arrow_path = drawingArrowPath.get(index);
            Paint paint = drawingLinePaint.get(index);
            canvas.drawPath(path, Paint);
            canvas.drawPath(arrow_path, Paint);
        }
    }

    private void drawArrow(Canvas canvas) {
        double angle = calculateAngle(startX, startY, mX, mY);

        float final_angle = (float) (180 - angle);

        Path arrow_path = new Path();

        Matrix arrow_matrix = new Matrix();

        arrow_matrix.postRotate(final_angle, mX, mY);

        arrow_path.moveTo(mX, mY);
        arrow_path.lineTo(mX - arrowWidth, mY + arrowLength);
        arrow_path.moveTo(mX, mY);
        arrow_path.lineTo(mX + arrowWidth, mY + arrowLength);
        arrow_path.lineTo(mX - (arrowWidth), mY + arrowLength);
        arrow_path.transform(arrow_matrix);

        canvas.drawPath(arrow_path, initPaint());
    }

    private void saveArrow() {
        if (mX == -1 || mY == -1) {
            return;
        }

        double angle = calculateAngle(startX, startY, mX, mY);

        float final_angle = (float) (180 - angle);

        Path arrow_path = drawingArrowPath.get(pathIndex - 1);

        Matrix arrow_matrix = new Matrix();

        arrow_matrix.postRotate(final_angle, mX, mY);

        arrow_path.moveTo(mX, mY);
        arrow_path.lineTo(mX - arrowWidth, mY + arrowLength);
        arrow_path.moveTo(mX, mY);
        arrow_path.lineTo(mX + arrowWidth, mY + arrowLength);
        arrow_path.lineTo(mX - (arrowWidth), mY + arrowLength);
        arrow_path.transform(arrow_matrix);
    }

    public double calculateAngle(double x1, double y1, double x2, double y2) {
        double angle = Math.toDegrees(Math.atan2(x2 - x1, y2 - y1));

        angle = angle + Math.ceil(-angle / 360) * 360; //Keep angle between 0 and 360

        return angle;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case ACTION_UP:
                actionUp(event);
                break;
            case ACTION_MOVE:
                actionMove(event);
                break;
            case ACTION_DOWN:
                actionDown(event);
                break;
        }
        invalidate();
        return true;
    }

    private void actionDown(MotionEvent event) {
        updateIndex(event);
        startX = event.getX();
        startY = event.getY();
    }

    private void actionMove(MotionEvent event) {
        mX = event.getX();
        mY = event.getY();
    }

    private void actionUp(MotionEvent event) {
        drawingLinePath.get(pathIndex - 1).lineTo(event.getX(), event.getY());
        saveArrow();
        startX = -1;
        startY = -1;
        mX = -1;
        mY = -1;
    }
}
0
Sagar Suthar