java - キャンバスに描画された新しいパスにボタンを表示する

Question

ユーザーが描画して保存してから共有できるキャンバスがあります。私が遭遇した問題は、保存ボタンが押されると共有ボタンに置き換えられることです。ユーザーが共有を押す代わりに、既存の画像の上に何か新しいものを描画した場合、新しいパスがあるかどうかを確認して、共有ボタンを削除して保存ボタンを再度表示するにはどうすればよいですか?

XML:

<FrameLayout
    android:id="@+id/viewd"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="3"
    android:orientation="vertical"
    android:layout_gravity="center" >
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="0dp"
        android:background="@drawable/bd"
        android:id="@+id/llFreeDraw" >
    </LinearLayout>
</FrameLayout>

私のペイントJavaクラス：

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.view.View;
import android.widget.TextView;

public class CustomView extends View {
    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());
            invalidate();
            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());
            invalidate();
            break;
        case MotionEvent.ACTION_CANCEL:
            break;
        default:
            break;
        }
        return true;
    }
}

私の MainActivity クラス:

layout = (FrameLayout)findViewById(R.id.viewd);
        //layout.removeAllViews();
        view = new CustomView(FreeDraw.this);
        view.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT));
        layout.addView(view);
...
    View.OnClickListener saveHandle = new View.OnClickListener() {
        public void onClick(View v) {
            new SaveImageTask().execute(null, null, null);
        }
    };
    public class SaveImageTask extends AsyncTask<Void, Void, Void> {
         @Override
         protected Void doInBackground(Void... params) { //Running in background
            View content = layout;
            content.setDrawingCacheEnabled(true);
            content.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
            Bitmap bitmap = content.getDrawingCache();
            File folder = new File(Environment.getExternalStorageDirectory() + "/PB");
            if (!folder.exists()) {
                folder.mkdir();
            }
            file = new File(folder + "/pb_image_" + Math.random()  + ".png");
            FileOutputStream ostream;
            try {
                file.createNewFile();
                ostream = new FileOutputStream(file);
                bitmap.compress(CompressFormat.PNG, 100, ostream);
                ostream.flush();
                ostream.close();
                isSaved = true;
            } catch (Exception e) {
                e.printStackTrace();
                isSaved = false;
            }
            return null;
         }

         @Override
         protected  void onPreExecute() { //Activity is on progress
             //displayToast("Your image is saving...");
             btnSave.setVisibility(View.GONE);
             btnShare.setVisibility(View.GONE);
             pb.setVisibility(View.VISIBLE);
         }

         @Override
         protected void onPostExecute(Void v) { //Activity is done...
            if (isSaved == true) {
                 displayToast("Image was saved.");
                 btnSave.setVisibility(View.GONE);
                 btnShare.setVisibility(View.VISIBLE);
                 pb.setVisibility(View.GONE);
             }
             if (isSaved == false) {
                 displayToast("Unable to save image. Try again later.");
                 btnSave.setVisibility(View.VISIBLE);
                 btnShare.setVisibility(View.GONE);
                 pb.setVisibility(View.GONE);
             }
         }
    }

新しいパスが描画された場合に SAVE ボタンを表示するにはどうすればよいですか?

やりたいことを引き出すイメージ... ここに画像の説明を入力

Paint クラスを次のように変更してみました。

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.view.View;
import android.widget.Button;
import android.widget.TextView;

public class CustomView extends View {
    Paint paint;
    Path path;
    float x = 0;
    float y = 0;
    private int cWhite = Color.WHITE;
    private Button btnS, btnSa;

    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);

        btnS = (Button) findViewById(R.id.shareButton);
        btnSa = (Button) findViewById(R.id.saveButton);
    }

    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());
            if (btnS.getVisibility() == View.VISIBLE && btnS != null) {
                btnS.setVisibility(View.GONE);
                btnSa.setVisibility(View.VISIBLE);
            }
            else {
                //do nothing...
            }
            invalidate();
            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());
            invalidate();
            break;
        case MotionEvent.ACTION_CANCEL:
            break;
        default:
            break;
        }
        return true;
    }
}

ACTION_DOWNSHARE ボタンを非表示にして SAVE ボタンを表示するために、イベントに次の行を追加しました。

    if (btnS.getVisibility() == View.VISIBLE && btnS != null) {
        btnS.setVisibility(View.GONE);
        btnSa.setVisibility(View.VISIBLE);
    }
    else {
        //do nothing...
    }

しかし、エラーが発生します、私の LogCat:

09-04 21:35:58.752: E/AndroidRuntime(3835): FATAL EXCEPTION: main
09-04 21:35:58.752: E/AndroidRuntime(3835): java.lang.NullPointerException
09-04 21:35:58.752: E/AndroidRuntime(3835):     at com.test.testing.CustomView.onTouchEvent(CustomView.java:47)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.View.dispatchTouchEvent(View.java:7246)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2174)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1875)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1953)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1405)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.app.Activity.dispatchTouchEvent(Activity.java:2410)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1901)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.View.dispatchPointerEvent(View.java:7426)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3220)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3165)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4292)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4271)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4363)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:179)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.os.MessageQueue.nativePollOnce(Native Method)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.os.MessageQueue.next(MessageQueue.java:125)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.os.Looper.loop(Looper.java:124)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at android.app.ActivityThread.main(ActivityThread.java:5195)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at java.lang.reflect.Method.invokeNative(Native Method)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at java.lang.reflect.Method.invoke(Method.java:511)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
09-04 21:35:58.752: E/AndroidRuntime(3835):     at dalvik.system.NativeStart.main(Native Method)

それを修正する方法またはステップを完了する方法について何か提案はありますか?

score 1 · Accepted Answer

NullPointerExceptionボタン参照がメソッドnull内にあるため、を取得します。onTouchEvent()これはfindViewById()、カスタムビューとその子でのみボタンを検索する直接ボタンを検索するために発生します。したがって、代わりに：

btnS = (Button) findViewById(R.id.shareButton);
btnSa = (Button) findViewById(R.id.saveButton);

ボタンとカスタムビューを含むActivity(コンストラクターで渡されるパラメーター)でボタンを探します。Context

btnS = (Button)((Activity) context).findViewById(R.id.shareButton);
btnSa = (Button)((Activity) context).findViewById(R.id.saveButton);.

java - キャンバスに描画された新しいパスにボタンを表示する

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