Question

我正在开发一个图库应用程序，我找到了这个教程。

http://www.androidhive.info/2013/09/android-fullscreen-image-slider-with-swipe-and-pinch-zoom-gestures/

项目作为图库应用程序运行（显示图像和滑动，放大和缩小功能）

正如您在项目中看到的那样，图像是从SD卡加载的。我有一个我的图像的网址，我想从这个网址加载图像，而不是使用SD卡。

所有建议都可能有所帮助。谢谢

我编辑了这个问题。

Answer 1

要从互联网下载图像，请创建一个扩展异步的类，并使用ImageView和url并返回位图：

类似的东西：

private class LoadImagefromUrl extends AsyncTask< Object, Void, Bitmap > {
        ImageView ivPreview = null;

        @Override
        protected Bitmap doInBackground( Object... params ) {
            this.ivPreview = (ImageView) params[0];
            String url = (String) params[1];
            System.out.println(url);
            return loadBitmap( url );
        }

        @Override
        protected void onPostExecute( Bitmap result ) {
            super.onPostExecute( result );
            ivPreview.setImageBitmap( result );
        }
    }

    public Bitmap loadBitmap( String url ) {
        URL newurl = null;
        Bitmap bitmap = null;
        try {
            newurl = new URL( url );
            bitmap = BitmapFactory.decodeStream( newurl.openConnection( ).getInputStream( ) );
        } catch ( MalformedURLException e ) {
            e.printStackTrace( );
        } catch ( IOException e ) {

            e.printStackTrace( );
        }
        return bitmap;
    }

在您的情况下，我相信您的touchImageView类扩展了ImageView，因此您可以将ImageView替换为您正在使用的View类。

然后从您持有视图的活动中可以说：

new LoadImagefromUrl( ).execute( imageView, url );

您不想在下载时保留用户界面希望有所帮助..

至于集成一个允许你的缩放功能的TouchImageView，请注意这个类你的链接包括：

<强> TouchImageView.java

package info.androidhive.imageslider.helper;


    import android.content.Context;
    import android.graphics.Matrix;
    import android.graphics.PointF;
    import android.graphics.drawable.Drawable;
    import android.util.AttributeSet;
    import android.util.Log;
    import android.view.MotionEvent;
    import android.view.ScaleGestureDetector;
    import android.view.View;
    import android.widget.ImageView;

    public class TouchImageView extends ImageView {

        Matrix matrix;

        // We can be in one of these 3 states
        static final int NONE = 0;
        static final int DRAG = 1;
        static final int ZOOM = 2;
        int mode = NONE;

        // Remember some things for zooming
        PointF last = new PointF();
        PointF start = new PointF();
        float minScale = 1f;
        float maxScale = 3f;
        float[] m;

        int viewWidth, viewHeight;
        static final int CLICK = 3;
        float saveScale = 1f;
        protected float origWidth, origHeight;
        int oldMeasuredWidth, oldMeasuredHeight;

        ScaleGestureDetector mScaleDetector;

        Context context;

        public TouchImageView(Context context) {
            super(context);
            sharedConstructing(context);
        }

        public TouchImageView(Context context, AttributeSet attrs) {
            super(context, attrs);
            sharedConstructing(context);
        }

        private void sharedConstructing(Context context) {
            super.setClickable(true);
            this.context = context;
            mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
            matrix = new Matrix();
            m = new float[9];
            setImageMatrix(matrix);
            setScaleType(ScaleType.MATRIX);

            setOnTouchListener(new OnTouchListener() {

                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    mScaleDetector.onTouchEvent(event);
                    PointF curr = new PointF(event.getX(), event.getY());

                    switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        last.set(curr);
                        start.set(last);
                        mode = DRAG;
                        break;

                    case MotionEvent.ACTION_MOVE:
                        if (mode == DRAG) {
                            float deltaX = curr.x - last.x;
                            float deltaY = curr.y - last.y;
                            float fixTransX = getFixDragTrans(deltaX, viewWidth,
                                    origWidth * saveScale);
                            float fixTransY = getFixDragTrans(deltaY, viewHeight,
                                    origHeight * saveScale);
                            matrix.postTranslate(fixTransX, fixTransY);
                            fixTrans();
                            last.set(curr.x, curr.y);
                        }
                        break;

                    case MotionEvent.ACTION_UP:
                        mode = NONE;
                        int xDiff = (int) Math.abs(curr.x - start.x);
                        int yDiff = (int) Math.abs(curr.y - start.y);
                        if (xDiff < CLICK && yDiff < CLICK)
                            performClick();
                        break;

                    case MotionEvent.ACTION_POINTER_UP:
                        mode = NONE;
                        break;
                    }

                    setImageMatrix(matrix);
                    invalidate();
                    return true; // indicate event was handled
                }

            });
        }

        public void setMaxZoom(float x) {
            maxScale = x;
        }

        private class ScaleListener extends
                ScaleGestureDetector.SimpleOnScaleGestureListener {
            @Override
            public boolean onScaleBegin(ScaleGestureDetector detector) {
                mode = ZOOM;
                return true;
            }

            @Override
            public boolean onScale(ScaleGestureDetector detector) {
                float mScaleFactor = detector.getScaleFactor();
                float origScale = saveScale;
                saveScale *= mScaleFactor;
                if (saveScale > maxScale) {
                    saveScale = maxScale;
                    mScaleFactor = maxScale / origScale;
                } else if (saveScale < minScale) {
                    saveScale = minScale;
                    mScaleFactor = minScale / origScale;
                }

                if (origWidth * saveScale <= viewWidth
                        || origHeight * saveScale <= viewHeight)
                    matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2,
                            viewHeight / 2);
                else
                    matrix.postScale(mScaleFactor, mScaleFactor,
                            detector.getFocusX(), detector.getFocusY());

                fixTrans();
                return true;
            }
        }

        void fixTrans() {
            matrix.getValues(m);
            float transX = m[Matrix.MTRANS_X];
            float transY = m[Matrix.MTRANS_Y];

            float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);
            float fixTransY = getFixTrans(transY, viewHeight, origHeight
                    * saveScale);

            if (fixTransX != 0 || fixTransY != 0)
                matrix.postTranslate(fixTransX, fixTransY);
        }

        float getFixTrans(float trans, float viewSize, float contentSize) {
            float minTrans, maxTrans;

            if (contentSize <= viewSize) {
                minTrans = 0;
                maxTrans = viewSize - contentSize;
            } else {
                minTrans = viewSize - contentSize;
                maxTrans = 0;
            }

            if (trans < minTrans)
                return -trans + minTrans;
            if (trans > maxTrans)
                return -trans + maxTrans;
            return 0;
        }

        float getFixDragTrans(float delta, float viewSize, float contentSize) {
            if (contentSize <= viewSize) {
                return 0;
            }
            return delta;
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            viewWidth = MeasureSpec.getSize(widthMeasureSpec);
            viewHeight = MeasureSpec.getSize(heightMeasureSpec);

            //
            // Rescales image on rotation
            //
            if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
                    || viewWidth == 0 || viewHeight == 0)
                return;
            oldMeasuredHeight = viewHeight;
            oldMeasuredWidth = viewWidth;

            if (saveScale == 1) {
                // Fit to screen.
                float scale;

                Drawable drawable = getDrawable();
                if (drawable == null || drawable.getIntrinsicWidth() == 0
                        || drawable.getIntrinsicHeight() == 0)
                    return;
                int bmWidth = drawable.getIntrinsicWidth();
                int bmHeight = drawable.getIntrinsicHeight();

                Log.d("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);

                float scaleX = (float) viewWidth / (float) bmWidth;
                float scaleY = (float) viewHeight / (float) bmHeight;
                scale = Math.min(scaleX, scaleY);
                matrix.setScale(scale, scale);

                // Center the image
                float redundantYSpace = (float) viewHeight
                        - (scale * (float) bmHeight);
                float redundantXSpace = (float) viewWidth
                        - (scale * (float) bmWidth);
                redundantYSpace /= (float) 2;
                redundantXSpace /= (float) 2;

                matrix.postTranslate(redundantXSpace, redundantYSpace);

                origWidth = viewWidth - 2 * redundantXSpace;
                origHeight = viewHeight - 2 * redundantYSpace;
                setImageMatrix(matrix);
            }
            fixTrans();
        }
    }

您可以简单地创建一个类似的类，并将其包含在xml布局中或附加到java中。使用TouchImageView将上面的引用替换为ImageView。

有关此问题的更多信息请参阅android docs ..

http://developer.android.com/training/custom-views/index.html

enter image description here

Answer 2

您可以使用Picasso库将远程图像加载到TouchImageView中。

 Picasso.with(MyActivity.this).load(urlOfImage).fit().centerInside().error(R.drawable.no_img).into(touchImageView);

您需要遵循build.gradle文件的依赖关系才能使用Picasso Library

compile 'com.squareup.picasso:picasso:2.3.3'

Answer 3

尝试这个，希望它有效

<强> MainActivity

public class MainActivity extends AppCompatActivity {

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

        ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
        ArrayList<String> articleList = getArticleData();

        ImageAdapter adapter = new ImageAdapter(this,articleList);
        viewPager.setAdapter(adapter);
    }

    private ArrayList<String> getArticleData() {
        ArrayList<String> articleList = new ArrayList<String>(Arrays.asList(MyArticleData.articles));


        return articleList;
    }
}

适用于网址

public class MyArticleData {

    static String[] articles = {

            "https://api.learn2crack.com/android/images/donut.png",
            "https://api.learn2crack.com/android/images/eclair.png",
            "https://api.learn2crack.com/android/images/froyo.png",
             ----
             -----
             ------
            https://api.learn2crack.com/android/images/donut.png"
           };
}

<强> ImageAdapter

public class ImageAdapter extends PagerAdapter {
    Context context;
    ArrayList<String> data = new ArrayList<>();
    public LayoutInflater mLayoutInflater;
    View imageView;

    ImageAdapter(Context context, ArrayList<String> urls) {
        this.context = context;
        this.data = urls;
    }
    @Override
    public int getCount() {
        return 30;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((ImageView) object);
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        ImageView imageView = new ImageView(context);
        int padding = context.getResources().getDimensionPixelSize(R.dimen.padding_medium);
        imageView.setPadding(padding, padding, padding, padding);
        imageView.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
        //imageView.setImageResource(GalImages[position]);

        Picasso.with(context).load(data.get(position)).into(imageView);
        ((ViewPager) container).addView(imageView, 0);
        return imageView;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        ((ViewPager) container).removeView((ImageView) object);
    }

}

<强> activity_main.xml中

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <android.support.v4.view.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

<强> pager_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <ImageView
        android:id="@+id/imageView"
        android:layout_height="fill_parent"
        android:layout_width="fill_parent"
        android:scaleType="centerCrop">
    </ImageView>

</LinearLayout>

使用URL Source而不是SD Card来加载图像

3 个答案: