An emerging technology like Android application development should be contributed to keen developers from other technology as well as other Android folks. A lot of essential techniques will be distributed in our society with complete source code through Github,
https://github.com/JayaprakashR-Zealot
If you are looking for an Animated line drawing in sequence, you are at the right place. We have to download SVG Android library (i.e. Add jar to lib folder svg-android-1.1.jar) to use SVG image in application.
Working Logic
I elucidate the working logic step by step. We have to load the svg from the resources and render the svg to canvas and catch all the paths while rendering.
public List<SvgPath> getPathsForViewport(final int width, final int height) {
final float strokeWidth = mSourcePaint.getStrokeWidth();
Canvas canvas = new Canvas() {
private final Matrix mMatrix = new Matrix();
@Overridepublic int getWidth() {
return width;
}
@Overridepublic int getHeight() {
return height;
}
@Overridepublic void drawPath(Path path, Paint paint) {
Path dst = new Path();
//noinspection deprecationgetMatrix(mMatrix);
path.transform(mMatrix, dst);
paint.setAntiAlias(true);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(strokeWidth);
mPaths.add(new SvgPath(dst, paint));
}
};
rescaleCanvas(width, height, strokeWidth, canvas);
return mPaths;
}
then rescale the canvas with specific width and height.
If we need to portray complex list with bulk content with slinky animation ( i.e. material design styles) in your apps, the better choice must be the RecyclerView and CardView widgets.
In this post, we are going to understand the how to populate images in Recycler view through horizontal direction with customized CardView layout. We also learn custom ItemAnimator, onItemClickListener for RecyclerView as well. This application shows a horizontal category RecyclerView that shows the images of shirt, pant, overcoat, hat, and etc. The choices populate based on selected category from Recycler View. You can find the workflow from below video.
If you want to use a RecyclerView, you will need to work with the following:
RecyclerView.Adapter - To handle the data collection and bind it to the view
LayoutManager - Helps in positioning the items
ItemAnimator - Helps with animating the items for common operations such as Addition or Removal of an item.
Moreover, the add or remove data in Listview had been extremely difficult to do. RecyclerView is mandatory to implement the ViewHolder Class that was already a recommended practice in Listview but now deeply integrated with this RecyclerView framework. You can find the detailed explanation for RecyclerView components here.
Why RecyclerView than ListView
Required ViewHolder in Adapters - ListView adapters do not require the use of the ViewHolder. In contrast, implementing an adapter for RecyclerView requires the use of the ViewHolder pattern for better performance.
Customizable Item Layouts - The RecyclerView has a RecyclerView.LayoutManager that allows any item layouts including horizontal lists or staggered grids.
Easy Item Animations - ListView contains no special provisions through which one can animate the addition or deletion of items. In contrast, the RecyclerView has the RecyclerView.ItemAnimator class for handling item animations.
Manual Data Source - ListView had adapters for different sources such as ArrayAdapter and CursorAdapter for arrays and database results respectively. In contrast, the RecyclerView.Adapter requires a custom implementation to supply the data to the adapter.
Manual Item Decoration - ListView has the android:divider property for easy dividers between items in the list. In contrast, RecyclerView requires the use of a RecyclerView.ItemDecoration object to setup much more manual divider decorations.
Manual Click Detection - ListView has a AdapterView.OnItemClickListener interface for binding to the click events for individual items in the list. In contrast, RecyclerView only has support for RecyclerView.OnItemTouchListener which manages individual touch events but has no built-in click handling.
Components of a RecyclerView
LayoutManager
A layout manager positions item views inside a RecyclerView and determines when to reuse item views that are no longer visible to the user. To reuse (or recycle) a view, a layout manager may ask the adapter to replace the contents of the view with a different element from the data set. Recycling views in this manner improve performance by avoiding the creation of unnecessary views or performing expensive layout id lookups.
LinearLayoutManager - shows items in a vertical or horizontal scrolling list.
GridLayoutManager - shows items in a grid.
StaggeredGridLayoutManager - shows items in a staggered grid.
RecyclerView.Adapter
RecyclerView is a similar approach to the ones you already used, but with some peculiarities, such as a required ViewHolder. You will have to override two main methods:
onCreateViewHolder() - One to inflate the view and its view holder.
onBindViewHolder() - One to bind data to the view.
The good thing about this is that first method is called only when we really need to create a new view. No need to check if it’s being recycled.
RecyclerView.ItemAnimator
The add/delete/select operations are notified to the adapter. DefaultItemAnimator can be used for basic default animations and works quite well.
RecyclerView.OnItemClickListener
By implementing the RecyclerView.OnItemTouchListener to respond to only single tap events. This is just a beginning and extended to provide more complex gestures like long click etc.
public class Category implements Serializable {
public String cat_name,cat_description;
public int cat_id,cat_icon;
}
Serializing a class file provides a fast and efficeint way to store information produced by your application.
Step 4: Creating Adapter class
The adapter's role is to convert an object to a position into a list row item to be inserted. However, with a RecyclerView the adapter requires the existence of a "ViewHolder" object which describes and provides access to all the views within each item row.
public class CategoryAdapter extends RecyclerView.Adapter<CategoryAdapter.AKCViewHolder>{
private Context mContext;
private List<Category> mCategoryList;
private final static int FADE_DURATION = 300; // in millisecondsprivate int lastPosition = -1;
public class AKCViewHolder extends RecyclerView.ViewHolder {
public ImageView categoryIcon;
public AKCViewHolder(View view) {
super(view);
categoryIcon = (ImageView) view.findViewById(R.id.categoryImage);
}
}
public CategoryAdapter(Context mContext, List<Category> cateList) {
this.mContext = mContext;
this.mCategoryList = cateList;
}
@Overridepublic AKCViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View categoryItem= LayoutInflater.from(parent.getContext()).inflate
(R.layout.list_single_card,parent,false);
return new AKCViewHolder(categoryItem);
}
@Overridepublic void onBindViewHolder(AKCViewHolder holder, int position) {
Category categoryItem=mCategoryList.get(position);
Bitmap icon = BitmapFactory.decodeResource(mContext.getResources(),categoryItem.cat_icon);
holder.categoryIcon.setImageBitmap(icon);
// Set the view to scale //setScaleAnimation(holder.categoryIcon);if(CATEGORY_SELECTED_POSITION == position){
// Here I am just highlighting the backgroundholder.categoryIcon.setBackgroundColor(mContext.getResources()
.getColor(R.color.colorPickedItem));
}else{
holder.categoryIcon.setBackgroundColor(mContext.getResources()
.getColor(R.color.colorItembg));
}
}
@Overridepublic int getItemCount() {
return mCategoryList.size();
}
}
Every adapter has three primary methods: onCreateViewHolder to inflate the item layout and create the holder, onBindViewHolder to set the view attributes based on the data and getItemCount to determine the number of items.
With the adapter completed, all that is remaining is to bind the data from the adapter into the RecyclerView.
In MainActivity.java binding adapter to RecyclerView.
Step 6: Assigning LayoutManager to RecyclerView
// Enable optimizations if the items are static and will not change for significantly smoother scrollingmCategoryRecyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager mCateLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
mCategoryRecyclerView.setLayoutManager(mCateLayoutManager);
We assign the HORIZONTAL orientation at LinearLayoutManager for RecyclerView. We have to setHasFixedSize(true) by enabling optimizations if the items are static and will not change for significantly smoother scrolling.
Call prepareCategory() in OnCreate() to load data in mCategoryList ArrayList. Finally, compile and run the app and you should see something like the screenshot below.
Step 7: Creating custom OnItemClickListener
An important point that the guide leaves out is about handling clicks on the recycler view items. There is no such thing as OnItemClickListener for RecyclerViews. Given that RecyclerView takes ListView
a step further and doesn't have a concept of a row/column, but rather
an arbitrarily laid out amount of children, they have delegated the onClick to each one of them, or to programmer implementation. So We should implement OnItemTouchListener to achieve this issue.
