Android GridView 项目在按下时更改图像并变回

Question

问题描述

在我的应用程序中，我有 GridView，其中包含 12 个项目。 GridView 中的每个项目都有自己的图标，如下图所示。对于每个图标，我都有两张图片，一张是按下的，一张是正常的。

问题

当用户按下项目然后释放按钮时，我尝试找到一些标准机制来将图像从正常状态更改为按下状态，但找不到。而不是我使用public boolean onTouch(View v, MotionEvent event) 方法，但它会带来一些副作用，例如当用户向下滚动或滑动屏幕以更改选项卡时，单击项目。

源代码

@Override
public boolean onTouch(View v, MotionEvent event) {
    /* Get Action on Touch. */
    int action = event.getActionMasked();
    if (action == MotionEvent.ACTION_DOWN) {
        float currentXPosition = event.getX();
        float currentYPosition = event.getY();
        
        lastPressedPosition = gvCategories.pointToPosition((int) currentXPosition, (int) currentYPosition);
        if(lastPressedPosition < 0 || lastPressedPosition > sDefaultArray.length)
            return false;
    
        /* Set Pressed Image. */
        Drawable drawable = getActivity().getResources().getDrawable(sPressedArray[lastPressedPosition]);
        Category category = (Category) gvCategories.getItemAtPosition(lastPressedPosition);
        category.setImage(((BitmapDrawable) drawable).getBitmap());
        CategoriesGridAdapter adapter = (CategoriesGridAdapter)gvCategories.getAdapter();
        adapter.notifyDataSetChanged();
        
    }
    else if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) {
        
        /* Get current possition to compare with the last one. */
        float currentXPosition = event.getX();
        float currentYPosition = event.getY();
        int currentPosition = gvCategories.pointToPosition((int) currentXPosition, (int) currentYPosition);
        if(currentPosition == -1 && lastPressedPosition == -1)
            return false;
        if (currentPosition == lastPressedPosition && action == MotionEvent.ACTION_UP) {
            
            Category category = (Category) gvCategories.getItemAtPosition(currentPosition);
            Log.i(TAG, String.format("Category Title is: %s", category.getTitle()));
            
            if (category == Category.More) {
                
                //tracker.trackEvent("Category Clicked", "More", "", 0L);
                
                /* Get current selected language. */
                final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
                final String lang = preferences.getString(Preferences.LANGUAGE, "en");
                /* Load All categories available in the application. */
                updateCategoriesAdapter(lang, true);
            }
            else {
                
                //tracker.trackEvent("Category Clicked", category.getTitle(), "", 0L);
                
                CategoryDetailsActivity.sFragmentManager = getFragmentManager();
                /* Start categories detail activity. */
                Intent intent = new Intent(getActivity().getApplicationContext(), CategoryDetailsActivity.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                intent.putExtra(CategoryDetailsActivity.CATEGORIES_IDS, category.getIDs());
                intent.putExtra(CategoryDetailsActivity.CATEGORY_NAME, category.getTitle());
                getActivity().getApplicationContext().startActivity(intent);
            }
            
            
        }
        
        if(lastPressedPosition == -1)
            return false;
        
        /* Set Pressed Image. */
        Drawable drawable = getActivity().getResources().getDrawable(sDefaultArray[lastPressedPosition]);
        Category category = (Category) gvCategories.getItemAtPosition(lastPressedPosition);
        category.setImage(((BitmapDrawable) drawable).getBitmap());
        CategoriesGridAdapter adapter = (CategoriesGridAdapter)gvCategories.getAdapter();
        adapter.notifyDataSetChanged();
    }

    return false;
}

Answer 1

如果您已经制作了两张图片，请在GridView 中使用 Button 元素，并将按钮的 Background 元素设置为可绘制的状态选择器。有关使选择器可绘制的 XML 声明，请参阅此链接 example here 。 对于您的场景，您必须为每个按钮创建不同的选择器 XML 文件。