
It's been a while now and I've been pretty busy with life, work, and other things, but at last here's a new version of the coverflow widget that I released a while back. There's not really much new functionality here, but I have cut down the amount of code needed by a lot. Gone are the CoverAbsSpinner and the CoverAdapterView classes and now we are left with just the CoverFlow class weighing in at less than 200 lines of code. Of course, you still have to instantiate it and populate it using an ImageAdapter so I'll also include the activity class for doing those tasks as well.
How to use
In your Android project create a package called com.example.coverflow, and in this place the CoverFlow class. Now all you need is an activity to instantiate the Coverflow widget in this example the activity class is called CoverflowExample. CoverFlowExample simply extends Activity and instantiates a Coverflow class in it's onCreate method. It also has an internal Class, ImageAdapter which we use as the adapter for the Coverflow widget, much as we would for a Gallery widget. It is also possible to use the Coverflow widget when it is specified in an XML layout file.
Background
The basic idea is that the Coverflow widget works very much like the standard Android Gallery widget, but with the addition of the rotation of the images. For more background information on the Coverflow widget see my original post here.
How to use
In your Android project create a package called com.example.coverflow, and in this place the CoverFlow class. Now all you need is an activity to instantiate the Coverflow widget in this example the activity class is called CoverflowExample. CoverFlowExample simply extends Activity and instantiates a Coverflow class in it's onCreate method. It also has an internal Class, ImageAdapter which we use as the adapter for the Coverflow widget, much as we would for a Gallery widget. It is also possible to use the Coverflow widget when it is specified in an XML layout file.
The CoverFlow and CoverflowExample classes are here:
/*
* Copyright (C) 2010 Neil Davies
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This code is base on the Android Gallery widget and was Created
* by Neil Davies neild001 'at' gmail dot com to be a Coverflow widget
*
* @author Neil Davies
*/
package com.example.coverflow;
import android.content.Context;
import android.graphics.Camera;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Transformation;
import android.widget.Gallery;
import android.widget.ImageView;
public class CoverFlow extends Gallery {
/**
* Graphics Camera used for transforming the matrix of ImageViews
*/
private Camera mCamera = new Camera();
/**
* The maximum angle the Child ImageView will be rotated by
*/
private int mMaxRotationAngle = 60;
/**
* The maximum zoom on the centre Child
*/
private int mMaxZoom = -120;
/**
* The Centre of the Coverflow
*/
private int mCoveflowCenter;
public CoverFlow(Context context) {
super(context);
this.setStaticTransformationsEnabled(true);
}
public CoverFlow(Context context, AttributeSet attrs) {
super(context, attrs);
this.setStaticTransformationsEnabled(true);
}
public CoverFlow(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.setStaticTransformationsEnabled(true);
}
/**
* Get the max rotational angle of the image
* @return the mMaxRotationAngle
*/
public int getMaxRotationAngle() {
return mMaxRotationAngle;
}
/**
* Set the max rotational angle of each image
* @param maxRotationAngle the mMaxRotationAngle to set
*/
public void setMaxRotationAngle(int maxRotationAngle) {
mMaxRotationAngle = maxRotationAngle;
}
/**
* Get the Max zoom of the centre image
* @return the mMaxZoom
*/
public int getMaxZoom() {
return mMaxZoom;
}
/**
* Set the max zoom of the centre image
* @param maxZoom the mMaxZoom to set
*/
public void setMaxZoom(int maxZoom) {
mMaxZoom = maxZoom;
}
/**
* Get the Centre of the Coverflow
* @return The centre of this Coverflow.
*/
private int getCenterOfCoverflow() {
return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft();
}
/**
* Get the Centre of the View
* @return The centre of the given view.
*/
private static int getCenterOfView(View view) {
return view.getLeft() + view.getWidth() / 2;
}
/**
* {@inheritDoc}
*
* @see #setStaticTransformationsEnabled(boolean)
*/
protected boolean getChildStaticTransformation(View child, Transformation t) {
final int childCenter = getCenterOfView(child);
final int childWidth = child.getWidth() ;
int rotationAngle = 0;
t.clear();
t.setTransformationType(Transformation.TYPE_MATRIX);
if (childCenter == mCoveflowCenter) {
transformImageBitmap((ImageView) child, t, 0);
} else {
rotationAngle = (int) (((float) (mCoveflowCenter - childCenter)/ childWidth) * mMaxRotationAngle);
if (Math.abs(rotationAngle) > mMaxRotationAngle) {
rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle : mMaxRotationAngle;
}
transformImageBitmap((ImageView) child, t, rotationAngle);
}
return true;
}
/**
* This is called during layout when the size of this view has changed. If
* you were just added to the view hierarchy, you're called with the old
* values of 0.
*
* @param w Current width of this view.
* @param h Current height of this view.
* @param oldw Old width of this view.
* @param oldh Old height of this view.
*/
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
mCoveflowCenter = getCenterOfCoverflow();
super.onSizeChanged(w, h, oldw, oldh);
}
/**
* Transform the Image Bitmap by the Angle passed
*
* @param imageView ImageView the ImageView whose bitmap we want to rotate
* @param t transformation
* @param rotationAngle the Angle by which to rotate the Bitmap
*/
private void transformImageBitmap(ImageView child, Transformation t, int rotationAngle) {
mCamera.save();
final Matrix imageMatrix = t.getMatrix();;
final int imageHeight = child.getLayoutParams().height;;
final int imageWidth = child.getLayoutParams().width;
final int rotation = Math.abs(rotationAngle);
mCamera.translate(0.0f, 0.0f, 100.0f);
//As the angle of the view gets less, zoom in
if ( rotation < mMaxRotationAngle ) {
float zoomAmount = (float) (mMaxZoom + (rotation * 1.5));
mCamera.translate(0.0f, 0.0f, zoomAmount);
}
mCamera.rotateY(rotationAngle);
mCamera.getMatrix(imageMatrix);
imageMatrix.preTranslate(-(imageWidth/2), -(imageHeight/2));
imageMatrix.postTranslate((imageWidth/2), (imageHeight/2));
mCamera.restore();
}
}
/*
* Copyright (C) 2010 Neil Davies
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This code is base on the Android Gallery widget and was Created
* by Neil Davies neild001 'at' gmail dot com to be a Coverflow widget
*
* @author Neil Davies
*/
package com.example.coverflow;
import java.io.FileInputStream;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuffXfermode;
import android.graphics.Bitmap.Config;
import android.graphics.PorterDuff.Mode;
import android.graphics.Shader.TileMode;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
public class CoverFlowExample extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
CoverFlow coverFlow;
coverFlow = new CoverFlow(this);
coverFlow.setAdapter(new ImageAdapter(this));
ImageAdapter coverImageAdapter = new ImageAdapter(this);
//coverImageAdapter.createReflectedImages();
coverFlow.setAdapter(coverImageAdapter);
coverFlow.setSpacing(-25);
coverFlow.setSelection(4, true);
coverFlow.setAnimationDuration(1000);
setContentView(coverFlow);
}
public class ImageAdapter extends BaseAdapter {
int mGalleryItemBackground;
private Context mContext;
private FileInputStream fis;
private Integer[] mImageIds = {
R.drawable.kasabian_kasabian,
R.drawable.starssailor_silence_is_easy,
R.drawable.killers_day_and_age,
R.drawable.garbage_bleed_like_me,
R.drawable.death_cub_for_cutie_the_photo_album,
R.drawable.kasabian_kasabian,
R.drawable.massive_attack_collected,
R.drawable.muse_the_resistance,
R.drawable.starssailor_silence_is_easy
};
private ImageView[] mImages;
public ImageAdapter(Context c) {
mContext = c;
mImages = new ImageView[mImageIds.length];
}
public boolean createReflectedImages() {
//The gap we want between the reflection and the original image
final int reflectionGap = 4;
int index = 0;
for (int imageId : mImageIds) {
Bitmap originalImage = BitmapFactory.decodeResource(getResources(),
imageId);
int width = originalImage.getWidth();
int height = originalImage.getHeight();
//This will not scale but will flip on the Y axis
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
//Create a Bitmap with the flip matrix applied to it.
//We only want the bottom half of the image
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false);
//Create a new bitmap with same width but taller to fit reflection
Bitmap bitmapWithReflection = Bitmap.createBitmap(width
, (height + height/2), Config.ARGB_8888);
//Create a new Canvas with the bitmap that's big enough for
//the image plus gap plus reflection
Canvas canvas = new Canvas(bitmapWithReflection);
//Draw in the original image
canvas.drawBitmap(originalImage, 0, 0, null);
//Draw in the gap
Paint deafaultPaint = new Paint();
canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);
//Draw in the reflection
canvas.drawBitmap(reflectionImage,0, height + reflectionGap, null);
//Create a shader that is a linear gradient that covers the reflection
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0,
bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff,
TileMode.CLAMP);
//Set the paint to use this shader (linear gradient)
paint.setShader(shader);
//Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
//Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width,
bitmapWithReflection.getHeight() + reflectionGap, paint);
ImageView imageView = new ImageView(mContext);
imageView.setImageBitmap(bitmapWithReflection);
imageView.setLayoutParams(new CoverFlow.LayoutParams(120, 180));
imageView.setScaleType(ScaleType.MATRIX);
mImages[index++] = imageView;
}
return true;
}
public int getCount() {
return mImageIds.length;
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
//Use this code if you want to load from resources
ImageView i = new ImageView(mContext);
i.setImageResource(mImageIds[position]);
i.setLayoutParams(new CoverFlow.LayoutParams(130, 130));
i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
//Make sure we set anti-aliasing otherwise we get jaggies
BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();
drawable.setAntiAlias(true);
return i;
//return mImages[position];
}
/** Returns the size (0.0f to 1.0f) of the views
* depending on the 'offset' to the center. */
public float getScale(boolean focused, int offset) {
/* Formula: 1 / (2 ^ offset) */
return Math.max(0, 1.0f / (float)Math.pow(2, Math.abs(offset)));
}
}
}
Code explanation
The CoverflowExample Code contains some extra code for creating reflections of the images, but apart from this is a standard activity class of the kind used with the Gallery widget.The CoverFlow class extends the Gallery widget , but now we override a few methods to allow us to transform the images before they are displayed. The most important method that we override is the getChildStaticTransformation method. Here I have to say thank you to a user called Nerdrow on the Android developers group who first showed me an example of overriding this method. By setting setStaticTransformationsEnabled in the constructors, we are telling the parent ViewGroup of the Coverflow class to invoke getChildStaticTransformation every time one of our images in drawn. In getChildStaticTransformation we simply calculate and apply a rotation and scale to the ImageView depending on it's position relative to the centre of the Coverflow widget. We also override the onSizeChanged method. This method is called every time the widget changes size e.g. when we change the orientation of the phone from portrait to landscape. In the onSizeChanged method we just get the centre position of the coverflow widget. There are also a few parameters that we can set, mZoomMax controls the maximum zoom of the central image and mMaxRotationAngle sets the maximum rotation angle of each image.
Thanks
Lastly, I just wanted to say thanks to everyone who has commented and given me feedback on the coverflow widget. It's be really positive and great to hear that people have got it working successfully on a range of devices such as the HTC magic , Motorolla droid and Nexus 1. There's still more to do for the coverflow widget and I'll release new version as and when I make updates. If anyone has anymore suggests for cool widgets or enhancements to this Coverflow widget then please do get in touch.
Hi,
Nice Widget Thanks for publishing! but where do i add coding to trigger a action when i click on the center image.
Hello!
I really like that widget! I would like to use it in my project but I dont know how... I would like Your widget to be in the middle of the screen. At the top and at the bottom of the screen I would like to have some text... But I have no idea how to do it :S (look at this pic: http://e.imagehost.org/0309/Untitled_20.png)
Would anyone be so nice and help me out? Thanks =)
Also: Please response to sjanamica's post :)
You can use this widget as you would the Gallery Widget. If you want it in the middle of the screen I would suggest using a vertical LinearLayout. For an example of specifying the widget in an XML layout file see my first post on Coverflow. For sjanamica's question, again you would do this as you would for the standard Gallery widget. If you don't know how have a search on the web or ask a question on one of the developer groups or stackoverflow.
Thanks for quick response and kindness =)
Hello,
Very interesting, really,
Do you think it should be possible to make it vertical?
BM
thanks a lot...very cool....i will use it in my code....
How use this coverflow with an XML Layout ?
In my XML file (main.xml) I have :
In my JAVA file I have :
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.main);
CoverFlow c = (CoverFlow)findViewById(R.id.coverflow);
coverFlow.setAdapter(new ImageAdapter(this));
}
But the layout on the emulator display but without the coverflow... What's the problem ?
Thanks a lot
Example given in this post of how to use with an XML layout: http://www.inter-fuser.com/2010/01/android-coverflow-widget.html
Indeed, it works very well with XML :)
Now how do you think about movements in the focused (most zoomed) JPG ?
Do you have some tips or anything else to help me in this idea of movement ?
Thanks a lot !
Hi
Very good article.
I'll have a question, is it possible to use a ImageButtonAdapter to retrieve the selection of the current image?
Ermmm, not sure off the top of my head. But essentially this is a Gallery widget, with transformations on the images. So look for examples of how to do this with the Gallery widget.
Hey Taf .... nice work ... Helped me alot ... I am having a problem with reflectioins ... Only the original image is shown ... reflection is not there ... Why is it so?
I haven't included the reflections in this example. Have a look at my previous example. And also the separate post That I did on creating reflections.
Hi taf,
Amazing job...thanks for sharing.
I am getting an out of memory exception when entering and leaving the activity (CoverflowExample) twice or three times. Is this something you are aware of or is it just me? (haven't made any changes to CoverflowExample except putting my own drawables in the mImageIds array...)
I read a bit about memory leaks: http://developer.android.com/intl/de/resources/articles/avoiding-memory-leaks.html
Is it possible that the line:
ImageView i = new ImageView(mContext); inside getView is causing it?
I can't say I've noticed this. I have seen problems in the previous example I did. When I was including the reflections in the images. That was just a quick hack to show the coverflow with reflections. I think the first thing I would try is taking out the drawable you've added and see if you still get the problem.
taf, thanks for your quick reply.
I replaced all the drawables with the default android icon and still got the same result.
Apparently one or more of the views keeps a hold of a reference to context-activity which the garbage collector can't release... problem is I can't tell which...
This is a bit of a quick guess, but I think I remember seeing a few posts on various groups that there may be a bug in the Gallery widget itself. Might be worth looking into. The way we set up the images here is the same as the way it is done for the original Gallery widget, have a look at a Gallery widget example. I can't think that what i've done would be causing memory leaks, I'm just doing transformations on each image, underneath it's still just the gallery widget
Not sure what you trying to do here, but as I've said before, this widget is essentially a standard gallery widget, so anything you can do with the gallery widget you should be able to do with this widget.
Hi taf,
i think u can't understand what i am trying ,simply i am trying click event work just like which is using in gallery : -
public void onItemClick(AdapterView arg0, View arg1, int position, long rowId)
{
System.out.println("-------- Simple Adapter ClickItem Working--------");
Toast.makeText(CoverFlowExample.this, "Selected Pic position"+position, Toast.LENGTH_LONG).show();
}
but this is not working not show any toast and print message in debug...
can u help me please what i am missing ...
Sorry I haven't got much time to look into this at the moment. As an aside you should use the Android logging rather than system.out.println for debug
Hello.
Many Thanks for posting this article.
I have two question that
1. How can I set the specific image to the center of cover flow?
2. How can I set selected images to the right and selected images to the left of the currently displayed image.?
Can anyone help me.? Thanks in Advance. :)
This widget is essentially a Gallery widget. look for how to do this with the Gallery widget, it should be the same for this widget.
Can you give an example of how to modify the size of the images in the widget? I've looked at Gallery and there's nothing to specify what the min/max size of images should be - nor do I see that easily in your code either. Any pointers would be great!
Currently the images are scaled to fit into the coverflow widget : i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
If you want this Widget to work with Views (instead of just Drawables), you can do this:
In the generatereflection method of the image adapter line 101 replace"
Bitmap originalImage = BitmapFactory.decodeResource(getResources(),
imageId);"
By "
View cardView = get this item's view;
cardView.measure(150, 183);
cardView.layout(0, 0, 150, 183);
cardView.setDrawingCacheEnabled(true);
Bitmap originalImage= cardView.getDrawingCache();
cardView.setDrawingCacheEnabled(false);
"
And in the CoverFlow class replace lines 169 and 170 replace "
final int imageHeight = child.getLayoutParams().height;
final int imageWidth = child.getLayoutParams().width;
"
By "
final int imageHeight = child.getHeight();
final int imageWidth = child.getWidth();
"
(for some reason, those two lines caused some bugs)
Thank you very much for this great widget :)
I'm gonna try to understand how it works
I did some modifications but the scroll is still real choppy on a HTC Legend. How's performance on your phone?
Performance was good on a G1. See the Video on my earlier post. I found that if I did to much in the getView method things would get choppy, but that was the same for the standard Gallery Widget.
hey taf, Excellent job..this is helping me a lot in my project...I have an idea which I tried in many ways but I am unable to succeed, my idea is: when I click at a point on the image, I want the images to be coming out from that point where I clicked" that is , scroll should start from the point I clicked, for this I want the point from where the scroll starts. Please help me. Can I get the starting point of the scroll.
I am not sure what you are trying to do. But i would suggest looking at n,earlier post i,did on coverflow. In that post i am,using the source code of the gallery widget. If you look at the,source for the gallery widget you may be able to,find,what you need.