在位图Android开发中绘制直线

Question

So I found this code online, but the problem is that instead of drawing a straight Line (Black Straight thin Line)instead it draws dotted lines, But everytime I modify it to draw a line I get an error. Any help would be appreciated.

package cameraadvanced.android2.oreillyschool.com.hello4;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.net.Uri;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import java.io.FileNotFoundException;

public class mic extends Activity {

    Button btnLoadImage;
    TextView textSource, textInfo;
    ImageView imageResult;

    final int RQS_IMAGE1 = 1;

    Uri source;
    Bitmap bitmapMaster;
    Canvas canvasMaster;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fingeract);

        btnLoadImage = (Button) findViewById(R.id.loadimage);
        textSource = (TextView) findViewById(R.id.sourceuri);
        imageResult = (ImageView) findViewById(R.id.result);

        btnLoadImage.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                Intent intent = new Intent(Intent.ACTION_PICK,
                        android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                startActivityForResult(intent, RQS_IMAGE1);
            }
        });

        imageResult.setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                int action = event.getAction();
                int x = (int) event.getX();
                int y = (int) event.getY();
                switch (action) {
                    case MotionEvent.ACTION_DOWN:
                        textSource.setText("ACTION_DOWN- " + x + " : " + y);
                        drawOnProjectedBitMap((ImageView) v, bitmapMaster, x, y);
                        break;
                    case MotionEvent.ACTION_MOVE:
                        textSource.setText("ACTION_MOVE- " + x + " : " + y);
                        drawOnProjectedBitMap((ImageView) v, bitmapMaster, x, y);
                        break;
                    case MotionEvent.ACTION_UP:
                        textSource.setText("ACTION_UP- " + x + " : " + y);
                        drawOnProjectedBitMap((ImageView) v, bitmapMaster, x, y);
                        break;
                }
    /*
     * Return 'true' to indicate that the event have been consumed.
     * If auto-generated 'false', your code can detect ACTION_DOWN only,
     * cannot detect ACTION_MOVE and ACTION_UP.
     */
                return true;
            }
        });

    }

    /*
     * Project position on ImageView to position on Bitmap
     * draw on it
     */
    private void drawOnProjectedBitMap(ImageView iv, Bitmap bm, int x, int y) {
        if (x < 0 || y < 0 || x > iv.getWidth() || y > iv.getHeight()) {
            //outside ImageView
            return;
        } else {
            int projectedX = (int) ((double) x * ((double) bm.getWidth() / (double) iv.getWidth()));
            int projectedY = (int) ((double) y * ((double) bm.getHeight() / (double) iv.getHeight()));

            Paint paint = new Paint();
            paint.setStyle(Paint.Style.FILL);
            paint.setColor(Color.WHITE);
            paint.setStrokeWidth(3);
            canvasMaster.drawCircle(projectedX, projectedY, 5, paint);
            imageResult.invalidate();

            textSource.setText(x + ":" + y + "/" + iv.getWidth() + " : " + iv.getHeight() + "\n" +
                            projectedX + " : " + projectedY + "/" + bm.getWidth() + " : " + bm.getHeight()
            );
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        Bitmap tempBitmap;

        if (resultCode == RESULT_OK) {
            switch (requestCode) {
                case RQS_IMAGE1:
                    source = data.getData();
                    textSource.setText(source.toString());

                    try {
                        //tempBitmap is Immutable bitmap,
                        //cannot be passed to Canvas constructor
                        tempBitmap = BitmapFactory.decodeStream(
                                getContentResolver().openInputStream(source));

                        Config config;
                        if (tempBitmap.getConfig() != null) {
                            config = tempBitmap.getConfig();
                        } else {
                            config = Config.ARGB_8888;
                        }

                        //bitmapMaster is Mutable bitmap
                        bitmapMaster = Bitmap.createBitmap(
                                tempBitmap.getWidth(),
                                tempBitmap.getHeight(),
                                config);

                        canvasMaster = new Canvas(bitmapMaster);
                        canvasMaster.drawBitmap(tempBitmap, 0, 0, null);

                        imageResult.setImageBitmap(bitmapMaster);
                    } catch (FileNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                    break;
            }
        }
    }
}

Answer 1

Read your code again. That's what drawOnProjectedBitMap does: it draws circles at specific points (current position). If you want lines instead of dots, you need to draw a line from the previous position to the current position.