padding does not work as expected in custom ViewGroup
Hi:
My layout have the following structure:
RelativeLayout(with padding)
MainView(ViewGroup)
And the activety_main.xml:
<RelativeLayout 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"
android:background="#ffffff"
android:paddingBottom="16dp"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="16dp"
tools:context=".MainActivity" >
<com.example.testandroid.MainView
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
MainView:
public class MainView extends ViewGroup {
public MainView(Context context, AttributeSet as) {
super(context);
addView(new MyView(context, null));
}
#Override
protected void dispatchDraw(Canvas canvas) {
canvas.drawColor(Color.GREEN);
super.dispatchDraw(canvas);
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
for (int i = 0, len = getChildCount(); i < len; i++) {
View v = getChildAt(i);
v.layout(l,t,r,b);
}
}
}
MyView:
public class MyView extends SurfaceView implements Callback {
public MyView(Context contex, AttributeSet as) {
super(contex, as);
getHolder().addCallback(this);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
refresh();
}
private void refresh() {
SurfaceHolder holder = getHolder();
synchronized (holder) {
Canvas canvas = holder.lockCanvas();
if (canvas != null) {
try {
Paint p = new Paint();
p.setColor(Color.RED);
canvas.drawCircle(10, 10, 10, p);
} finally {
holder.unlockCanvasAndPost(canvas);
}
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
refresh();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}
Now, this is what I got now:
As you can see, the viewgroup I created MainView has a background of green.
And MainView add a MyView dynamically whose background is black here.
Now, the problem is that what the MyView have a padding relative to MainView? Because I want it take all the space of MainView, that's to say, the greed should be invisible.
Why?
But
When you layout your children, it needs to be relative to your position.
To fill yourself you would do child.layout(0, 0, getWidth(), getHeight());.
Try doing this ...
<RelativeLayout 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"
android:layout_margin="16dp"
tools:context=".MainActivity" >
<com.example.testandroid.MainView
android:layout_width="match_parent"
android:layout_height="600dp"
/>
</RelativeLayout>
Related
I didn't describe the question in a good way, so I edit the question to be clear.
I am so confused about this: I wrote a RelativeLayout with a DragViewGroup and a gridview, and I noticed that every time when I used notifyDatasetChanged() method would cause the DragViewGroup do the redrawing thing.And the DragViewGroup extends from LinearLayout which uses ViewDragHelper, so I could not maintain the position already scrolled to.
Here is my xml file:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.xxxx.DragViewGroup
android:id="#+id/dragview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#3f83f7"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="665dp"
android:orientation="vertical">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="310dp"
android:id="#+id/mainview"
>
...
</RelativeLayout>
<include
android:layout_width="match_parent"
android:layout_height="355dp"
android:layout_marginBottom="62dp"
layout="#layout/fake_panel" />
</LinearLayout>
</com.xxxx.DragViewGroup>
<RelativeLayout
android:layout_width="match_parent"
android:id="#+id/layout"
android:layout_alignParentBottom="true"
android:layout_height="210dp"
android:background="#ffffff"
android:clickable="true"
>
<HorizontalScrollView
android:id="#+id/btn_scroll_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:overScrollMode="never"
android:layout_alignParentBottom="true"
android:layout_marginBottom="26dp"
android:scrollbars="none">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<GridView
android:id="#+id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="10dp"
android:listSelector="#color/transparent"
android:horizontalSpacing="6dp"
android:scrollbars="none" />
</LinearLayout>
</HorizontalScrollView>
<com.xxxx.UniversalSeekBar
....
android:layout_marginTop="18dp"/>
</RelativeLayout>
</RelativeLayout>
DragViewGroup code:
public class DragViewGroup extends LinearLayout {
private ViewDragHelper viewDragHelper;
private View mainView;
private int mainHeight;
public DragViewGroup(Context context) {
super(context);
initView();
}
public DragViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
public DragViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView();
}
#Override
protected void onFinishInflate() {
super.onFinishInflate();
mainView = getChildAt(0);
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mainHeight = mainView.findViewById(R.id.mainview).getMeasuredHeight();
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
return viewDragHelper.shouldInterceptTouchEvent(ev);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
viewDragHelper.processTouchEvent(event);
return true;
}
#Override
public void computeScroll() {
if (viewDragHelper.continueSettling(true)) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
private void initView() {
viewDragHelper = ViewDragHelper.create(this, callback);
}
private ViewDragHelper.Callback callback = new ViewDragHelper.Callback() {
#Override
public boolean tryCaptureView(View child, int pointerId) {
return mainView == child;
}
#Override
public int clampViewPositionHorizontal(View child, int left, int dx) {
return 0;
}
#Override
public int clampViewPositionVertical(View child, int top, int dy) {
return top;
}
#Override
public void onViewReleased(View releasedChild, float xvel, float yvel) {
super.onViewReleased(releasedChild, xvel, yvel);
if (mainView.getTop() > -500) {
viewDragHelper.smoothSlideViewTo(mainView, 0, 0);
ViewCompat.postInvalidateOnAnimation(DragViewGroup.this);
} else {
viewDragHelper.smoothSlideViewTo(mainView, 0, -mainHeight);
ViewCompat.postInvalidateOnAnimation(DragViewGroup.this);
}
}
};
}
Once I use the notifyDatasetChanged() method to update the gridview, my DragViewGroup will slide to the original position itself although it has been dragged before. Apparently the method draw the whole layout instead of only drawing gridview itself.
I need to maintain the dragged position of DragViewGroup, I have tried that override onDraw method in DragViewGroup like this:
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// set isDragged label in onViewReleased()
if (isDragged) {
viewDragHelper.smoothSlideViewTo(main, 0, -mainHeight);
}
}
It works, but there is a visible sliding process which I don't want.
Hope someone could help me.Thanks very much.
Store ScrollValue at the time of the scrolling the view, and just use setSelectionMethod on your gridview
gridview.setOnScrollListener(new OnScrollListener() {
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
int count = gridview.getCount();
if (scrollState == SCROLL_STATE_IDLE) {
if (gridview.getLastVisiblePosition() >= count
- 1) {
scrollPos = <positionOfList>;
}
}
}
});
Here enter your last position insted of "positionOfList"
And just after calling notifydatasetChanged() call gridview.setSelection(scrollPos)
Hope this will help you!
Just use bellow code in class that you update display:
int index = myList.getFirstVisiblePosition();
View v = myList.getChildAt(0);
int top = (v == null) ? 0 : v.getTop();
myList.setAdapter(adapter);
adapter.notifyDataSetChanged();
myList.setSelectionFromTop(index, top);
I have RecycleViewer with Canvas view in list item. How can I change backgrouncolor of Canvas view in my RecycleViewerAdapter ?
Below is my onBindViewHolder method in my RecycleViewerAdapter
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.openprice.setText(mopenPrice.get(position));
//How can I change backgrouncolor canvas view ????
}
my ViewHolder
public ViewHolder(View itemView) {
super(itemView);
openprice = (TextView) itemView.findViewById(R.id.openprice);
viewx = (View) itemView.findViewById(R.id.viewx);
}
itemlist.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="80dp"
android:background="#drawable/border_listfavorite"
>
<view class="com.eusecom.exforu.MyView"
android:layout_width="fill_parent"
android:layout_height="20dp"
android:layout_alignParentLeft="true"
android:id="#+id/viewx"/>
<TextView
android:id="#+id/opentxt"
android:text="#string/opentxt"
android:singleLine="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/viewx"
/>
<TextView
android:id="#+id/openprice"
android:singleLine="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#+id/opentxt"
android:layout_below="#+id/viewx"
/>
</RelativeLayout>
MyView.java
public class MyView extends View {
public MyView(Context cxt, AttributeSet attrs) {
super(cxt, attrs);
setMinimumHeight(100);
setMinimumWidth(100);
}
#Override
protected void onDraw(Canvas cv) {
cv.drawColor(Color.WHITE);
Paint p = new Paint();
p.setColor(Color.GREEN);
p.setStrokeWidth(5);
cv.drawLine(20, 0, 20, cv.getHeight(), p);
}
}
Use invalidate() method for calling onDraw method.
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.viewx.setText(mopenPrice.get(position));
if(condition){
holder.viewx.setCustomColor(Color.GREEN);
holder.viewx.invalidate();
}
}
public class MyView extends View {
private int color = Color.WHITE;
public MyView(Context cxt, AttributeSet attrs) {
super(cxt, attrs);
setMinimumHeight(100);
setMinimumWidth(100);
}
#Override
protected void onDraw(Canvas cv) {
cv.drawColor(color);
Paint p = new Paint();
p.setColor(Color.GREEN);
p.setStrokeWidth(5);
cv.drawLine(20, 0, 20, cv.getHeight(), p);
}
public void setCustomColor(int color){
this.color = color;
}
public ViewHolder(View itemView) {
private MyView viewx;
super(itemView);
openprice = (TextView) itemView.findViewById(R.id.openprice);
viewx = (MyView) itemView.findViewById(R.id.viewx);
}
I want to create a custom view which should be added in another custom view.
The second view will be a container, so it should be able to contain the first view as its child.
For creating this views I am extending ViewGroup & LinearLayout classes.
Child view class is NodeView
public class NodeView extends LinearLayout
{
private final static String TAG = "NodeView";
private ImageView ivTop;
private ImageView ivBottom;
private Context myContext;
public NodeView(Context context, AttributeSet attrs)
{
super(context, attrs);
this.myContext = context;
setOrientation(LinearLayout.VERTICAL);
setGravity(Gravity.CENTER);
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(R.layout.view_test_multi, this, true);
ivTop = (ImageView) getChildAt(0);
ivBottom = (ImageView) getChildAt(2);
ivTop.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
Toast.makeText(myContext, "Top Clicked", Toast.LENGTH_SHORT).show();
}
});
ivBottom.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v)
{
Toast.makeText(myContext, "Bottom Clicked", Toast.LENGTH_SHORT).show();
}
});
}
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
}
public NodeView(Context context)
{
this(context, null);
}
}
& the container class is TreeViewGroup
public class TreeViewGroup extends ViewGroup
{
private static final String TAG = "CustomTreeNodeView";
NodeView nodeView;
public TreeViewGroup(Context context, AttributeSet attrs, int defStyleAttr)
{
super(context, attrs, defStyleAttr);
nodeView = new NodeView(getContext());
addView(nodeView);
}
public TreeViewGroup(Context context, AttributeSet attrs)
{
this(context, attrs, 0);
}
public TreeViewGroup(Context context)
{
this(context, null, 0);
}
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
}
}
& xml layout for node view is view_test_multi.xml
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android" >
<ImageView
android:layout_width="15dp"
android:layout_height="15dp"
android:layout_centerVertical="true"
android:src="#drawable/point_grey" />
<ImageView
android:layout_width="35dp"
android:layout_height="35dp"
android:layout_centerVertical="true"
android:src="#drawable/point_red" />
<ImageView
android:layout_width="15dp"
android:layout_height="15dp"
android:layout_centerVertical="true"
android:src="#drawable/point_grey" />
</merge>
My activity's layout is activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:custom="http://schemas.android.com/apk/res/com.ab1209.testcustom"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<com.ab1209.testcustom.view.TreeViewGroup
android:id="#+id/activity_main_custom_tree_node_view"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
MainActivity class is
**public class MainActivity extends Activity
{
TreeViewGroup treeNodeView;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
treeNodeView = (TreeViewGroup) findViewById(R.id.activity_main_custom_tree_node_view);
}
}**
When I run the app I don't see the NodeView added in main View. Am I doing the right thing if not please tell me how can I make it working?
To create a custom ViewGroup, the only method you need to override is
onLayout. The onLayout is triggered after the ViewGroup itself has
finished laying itself out inside its own container ViewGroup and is
now responsible for laying out its children. It should call the layout
method on all of its children to now position and size them (the left
and top parameters will determine the child view’s x and y and the
right and bottom will determine its width (right – left) and height
(top-bottom).
So your TreeViewGroup code will look like :
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int count = getChildCount();
for (int i = 0; i < count; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
ViewGroup.LayoutParams lp = (ViewGroup.LayoutParams) child
.getLayoutParams();
int childLeft = 0;
int childTop = 0;
child.layout(childLeft, childTop,
childLeft + child.getMeasuredWidth(),
childTop + child.getMeasuredHeight());
}
}
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
measureChildren(widthMeasureSpec, heightMeasureSpec);
int measuredWidth = 200; // Calculate the height
int measuredHeight = 200; // Calculate the width
setMeasuredDimension(measuredWidth, measuredHeight);
}
Refer this link http://arpitonline.com/2012/07/01/creating-custom-layouts-for-android/
What I am trying to achieve:
measure a container View in my layout, mainContainer, that is defined in the XML
pass the mainContainer's width and height to a different custom View before onDraw() is called
I want to pass the width and height so the custom View knows where to draw canvas.drawBitmap using coordinates
The custom view will be programmatically created from code
How can I pass the measured int width and int height to my custom View before onDraw() is called?
Custom View
public class AvatarView extends ImageView {
private Bitmap body;
private Bitmap hat;
public AvatarView(Context context) {
super(context);
init();
}
public AvatarView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public AvatarView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
body = BitmapFactory.decodeResource(getResources(), R.drawable.battle_run_char);
hat = BitmapFactory.decodeResource(getResources(), R.drawable.red_cartoon_hat);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(body, x, y, null);
canvas.drawBitmap(hat, x, y, null);
}
}
Fragment
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_customize_avatar, container, false);
final RelativeLayout mainContainer = (RelativeLayout) view.findViewById(R.id.main_container);
TwoWayView inventoryList = (TwoWayView) view.findViewById(R.id.inventory);
inventoryList.setAdapter(null);
inventoryList.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
}
});
mainContainer.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#SuppressLint("NewApi")
#SuppressWarnings("deprecation")
#Override
public void onGlobalLayout() {
// Retrieve the width and height
containerWidth = mainContainer.getWidth();
containerHeight = mainContainer.getHeight();
// Remove global listener
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN)
mainContainer.getViewTreeObserver().removeOnGlobalLayoutListener(this);
else
mainContainer.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
});
return view;
}
XML
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:clickable="true"
android:background="#fff" >
<com.walintukai.lfdate.CustomTextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:paddingTop="10dp"
android:paddingBottom="10dp"
android:textStyle="bold"
android:textColor="#fff"
android:textSize="20sp"
android:textAllCaps="true"
android:text="#string/customize_avatar"
android:background="#009BFF" />
<RelativeLayout
android:id="#+id/main_container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<org.lucasr.twowayview.TwoWayView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/inventory"
style="#style/HorizontalListView"
android:layout_width="match_parent"
android:layout_height="80dp"
android:drawSelectorOnTop="false"
android:background="#f3f3f3" />
</LinearLayout>
What you need to do is add a flag inside your AvatarView that checks if are you going to render this or not in your onDraw method.
sample:
public class AvatarView extends ImageView {
private Bitmap body;
private Bitmap hat;
private int containerHeight;
private int containerWidth;
private boolean isRender = false;
public AvatarView(Context context) {
super(context);
init();
}
public AvatarView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public AvatarView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public void setMeasure(int containerWidth, int containerHeight )
{
this.containerHeight = containerHeight;
this.containerWidth = containerWidth;
}
private void init() {
body = BitmapFactory.decodeResource(getResources(), R.drawable.battle_run_char);
hat = BitmapFactory.decodeResource(getResources(), R.drawable.red_cartoon_hat);
}
public void setRender(boolean render)
{
isRender = render;
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if(isRender )
{
canvas.drawBitmap(body, x, y, null);
canvas.drawBitmap(hat, x, y, null);
}
}
}
Now it wont render when you dont call setRender and set it to true. And just call setMeasure to pass the value.
First you need to call setMeasure and after you set the measure you then call setRender(true) and call invalidate() to call the onDraw method to render the images
I have custom SurfaceView, setting a background in onDraw method, then drawing canvas, but see only background. How can I draw with canvas on a background?
Tried to add a background with canvas, it works, but at top left 2-3dp was deleted, and redrawing every time background will eat a lot of memory.
So can it be done with 1st method or 2nd without empty spaces on top left?
Edit...
GameView.java
public class GameView extends SurfaceView {
private Bitmap background;
private SurfaceHolder holder;
private GameManager gameLoopThread;
public GameView(Context context, AttributeSet attrs) {
super(context, attrs, 0);
setWillNotDraw(false);
gameLoopThread = new GameManager(this);
holder = getHolder();
holder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
gameLoopThread.setRunning(false);
while (retry) {
try {
gameLoopThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
gameLoopThread.setRunning(true);
gameLoopThread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
});
background = BitmapFactory.decodeResource(getResources(), R.drawable.icon);
}
public void onDraw(Canvas canvas) {
canvas.drawBitmap(background, 0, 0, null);
}
public void drawCanvas(Canvas canvas) {
if (x < getWidth() - 10) {
x += 10;
} else {
gameLoopThread.setRunning(false);
}
canvas.drawLine(0, 200, x, 200, paint);
}
}
GameManager.java
public class GameManager extends Thread {
private GameView view;
private boolean running = false;
public GameManager(GameView view) {
this.view = view;
}
public void setRunning(boolean run) {
running = run;
}
#Override
public void run() {
while (running) {
Canvas c = null;
try {
c = view.getHolder().lockCanvas();
synchronized (view.getHolder()) {
view.drawCanvas(c);
}
} finally {
if (c != null) {
view.getHolder().unlockCanvasAndPost(c);
}
}
}
}
}
MainActivity.java
public class MainActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
LinearLayout ll = (LinearLayout) findViewById(R.id.main);
ll.setLayoutParams(new LinearLayout.LayoutParams(640, 400));
}
}
Main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:gravity="center_horizontal|top">
<LinearLayout
android:id="#+id/main"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<com.android.GameView
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>
The result is http://oi57.tinypic.com/15znrpy.jpg
If I comment GameView onDraw method and add canvas.drawBitmap(background, 0, 0, null); to drawCanvas the result will be
http://oi60.tinypic.com/t0g802.jpg
There's not really a specific way to set a SurfaceView's background.
If you set a background in onDraw then draw to the canvas somewhere outside of onDraw, it's going to call onDraw and draw the background over whatever was just drawn.
Redrawing the background every time will not eat a significant amount of memory, assuming you're not trying to do it on the UI thread.
Also, I'm not quite sure what you mean by "at top left 2-3dp was deleted" and "empty spaces on top left". Can you post an image of this, along with the code you've tried?