更改颜色而不影响先前绘制的任何内容

Question

我CustomView在应用程序中使用以下绘画工具：

package com.test.testing;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Paint.Style;
import android.view.MotionEvent;
import android.widget.TextView;

public class CustomView extends TextView {
    Paint paint;
    Path path;
    float x = 0;
    float y = 0;
    private int cWhite = Color.WHITE;

    public CustomView(Context context) {
        super(context);
        paint = new Paint();
        path= new Path();
        paint.setAlpha(255);
        paint.setColor(cWhite);
        paint.setStyle(Style.STROKE);
        paint.setStrokeWidth(20);
    }

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawPath(path,paint);
        canvas.drawCircle(x, y, 10, paint);
    }

    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getAction();
        switch (action) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(event.getX(), event.getY());
            path.lineTo(event.getX(), event.getY());
            break;
        case MotionEvent.ACTION_MOVE:
            x = event.getX();
            y = event.getY();
            path.lineTo(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_UP:
            path.lineTo(event.getX(), event.getY());
            break;
        case MotionEvent.ACTION_CANCEL:
            break;
        default:
            break;
        }
        return true;
    }
}

我设置了一个FrameLayout，用于在我的XML中保留用于绘制的画布：

<FrameLayout
    android:id="@+id/viewd"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="3"
    android:orientation="vertical" >
</FrameLayout>

我在内部调用Activity以获取使用户能够使用的视图：

layout = (FrameLayout)findViewById(R.id.viewd);
//layout.removeAllViews();
view = new CustomView(Activity.this);
view.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT));
layout.addView(view);

我有不同的颜色选项，用户可以从改变油漆笔触颜色的选择Dialog我之内Activity：

public void colorHandle() {
    // custom dialog
    final Dialog dialog = new Dialog(this);
    dialog.setContentView(R.layout.colorlayout);
    dialog.setTitle("Choose a Drawing Color");

    Button btnWH = (Button) dialog.findViewById(R.id.btnWhite);
    Button btnBL = (Button) dialog.findViewById(R.id.btnBlack);
    Button btnBLU = (Button) dialog.findViewById(R.id.btnBlue);
    Button btnCY = (Button) dialog.findViewById(R.id.btnCyan);
    Button btnDG = (Button) dialog.findViewById(R.id.btnDkGray);
    Button btnGR = (Button) dialog.findViewById(R.id.btnGray);
    Button btnGRE = (Button) dialog.findViewById(R.id.btnGreen);
    Button btnLG = (Button) dialog.findViewById(R.id.btnLtGray);
    Button btnMG = (Button) dialog.findViewById(R.id.btnMagenta);
    Button btnRD = (Button) dialog.findViewById(R.id.btnRed);
    Button btnYE = (Button) dialog.findViewById(R.id.btnYellow);

    if (btnWH != null) {
        btnWH.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.WHITE);
                dialog.dismiss();
            }
        });
    }
    if (btnBL != null) {
        btnBL.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.BLACK);
                dialog.dismiss();
            }
        });
    }
    if (btnBLU != null) {
        btnBLU.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.BLUE);
                dialog.dismiss();
            }
        });
    }
    if (btnCY != null) {
        btnCY.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.CYAN);
                dialog.dismiss();
            }
        });
    }
    if (btnDG != null) {
        btnDG.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.DKGRAY);
                dialog.dismiss();
            }
        });
    }
    if (btnGR != null) {
        btnGR.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.GRAY);
                dialog.dismiss();
            }
        });
    }
    if (btnGRE != null) {
        btnGRE.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.GREEN);
                dialog.dismiss();
            }
        });
    }
    if (btnLG != null) {
        btnLG.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.LTGRAY);
                dialog.dismiss();
            }
        });
    }
    if (btnMG != null) {
        btnMG.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.MAGENTA);
                dialog.dismiss();
            }
        });
    }
    if (btnRD != null) {
        btnRD.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.RED);
                dialog.dismiss();
            }
        });
    }
    if (btnYE != null) {
        btnYE.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                view.paint.setColor(Color.YELLOW);
                dialog.dismiss();
            }
        });
    }
    dialog.show();
}

除了我每次选择一种新的颜色外，其他所有东西都工作正常，以前绘制的任何内容也将更改为新选择的颜色。无论接下来选择什么新颜色，如何保持以前绘制的内容不变？

Answer 1

您将为每个TouchEvent添加到单个路径。然后使用“
Paint”颜色的当前值绘制“路径”。这就是为什么您会看到所有颜色都是单色的原因。您将需要为每种颜色更改创建单独的路径和颜色，然后按顺序绘制它们，并为每个drawPath（）调用更改Paint的颜色

我不这么认为。开辟道路并不坏。

List<Pair<Path, Integer>> path_color_list = new ArrayList<Pair<Path,Integer>>()

然后每次您更改颜色。使用当前路径和view.paint.getColor并将其保存到列表中。

path_color_list.add( new Pair.create(path, view.paint.getColor());
path = new Path();

然后在您的draw（）中遍历path_color_list，每次设置新的绘画颜色

for (Pair<Path,Integer> path_clr : path_color_list ){
   paint.setColor(path_clr.second);
  canvas.drawPath( path_clr.first, paint);
}

其次是您拥有的最后一个drawPath（）