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package com.dahai.demo;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;

/**
 * 作者： 大海
 * 时间： 2018/10/30
 * 描述：
 */
public class PaintView extends View {

    private Paint mPaint;
    private Path mPath;
    private Bitmap mBitmap;
    private Canvas mCanvas;
    
    public PaintView(Context context) {
        super(context);
        init();
    }

    public PaintView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public PaintView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStrokeWidth(5);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(Color.BLACK);

        mPath = new Path();

        mBitmap = Bitmap.createBitmap(getScreenWidth(getContext()), getScreenHeight(getContext()), Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawBitmap(mBitmap, 0, 0, null);
        canvas.drawPath(mPath, mPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                float currentX = x;
                float currentY = y;
                mPath.moveTo(currentX, currentY);
                break;
            case MotionEvent.ACTION_MOVE:
                currentX = x;
                currentY = y;
                mPath.quadTo(currentX, currentY, x, y); // 画线
                break;
            case MotionEvent.ACTION_UP:
                mCanvas.drawPath(mPath, mPaint);
                break;
        }

        invalidate();
        return true;
    }
    
    public Bitmap getPaintBitmap(int width,int height) {
        return resizeImage(mBitmap, width, height);
    }

    public Bitmap getPaintBitmap() {
        return getPaintBitmap(320, 480);
    }

    public Path getPath() {
        return mPath;
    }

    // 缩放
    public static Bitmap resizeImage(Bitmap bitmap, int width, int height) {
        int originWidth = bitmap.getWidth();
        int originHeight = bitmap.getHeight();

        float scaleWidth = ((float) width) / originWidth;
        float scaleHeight = ((float) height) / originHeight;

        Matrix matrix = new Matrix();
        matrix.postScale(scaleWidth, scaleHeight);
        return Bitmap.createBitmap(bitmap, 0, 0, originWidth, originHeight, matrix, true);
    }

    //清除画板
    public void clear() {
        if (mCanvas != null) {
            mPath.reset();
            mCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
            invalidate();
        }
    }

    private int getScreenWidth(Context context) {
        DisplayMetrics metric = new DisplayMetrics();
        ((Activity) context).getWindowManager().getDefaultDisplay()
                .getMetrics(metric);
        return metric.widthPixels;
    }

    private int getScreenHeight(Context context) {
        DisplayMetrics metric = new DisplayMetrics();
        ((Activity) context).getWindowManager().getDefaultDisplay()
                .getMetrics(metric);
        return metric.heightPixels;
    }
}

package com.dahai.demo;

import android.app.Dialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.FrameLayout;
import android.widget.Toast;

/**
 * 作者： 大海
 * 时间： 2018/10/30
 * 描述：
 */
public class WritePadDialog extends Dialog {
    private Context mContext;
    private WriteDialogListener mWriteDialogListener;
    private PaintView mPaintView;

    public WritePadDialog(Context context,
                          WriteDialogListener writeDialogListener) {
        super(context);
        this.mContext = context;
        this.mWriteDialogListener = writeDialogListener;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.write_pad);

        FrameLayout mFrameLayout = findViewById(R.id.tablet_view);
        mPaintView = new PaintView(mContext);
        mFrameLayout.addView(mPaintView);
        mPaintView.requestFocus();
        
        findViewById(R.id.write_pad_ok).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                if (mPaintView.getPath().isEmpty()) {
                    Toast.makeText(mContext, "空白的", Toast.LENGTH_SHORT).show();
                    return;
                }
                mWriteDialogListener.onPaintDone(mPaintView.getPaintBitmap());
                dismiss();
            }
        });

        findViewById(R.id.write_pad_clear).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mPaintView.clear();
            }
        });
        
        findViewById(R.id.write_pad_cancel).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                cancel();
            }
        });
    }

    public interface WriteDialogListener {
        void onPaintDone(Bitmap bitmap);
    }
}