Drawing with a canvas over an ImageView - android

I want to create an ImageView and then draw text on top of the ImageView. I also need to be able to modify the text periodically. Currently I've created a custom view that extends ImageView. Then I overwrite onDraw() and use it to draw the text. Only problem then is that when I use my custom ImageView it doesn't draw the image, just the text.
public class BoardView extends ImageView
{
public BoardView(Context context)
{
super(context);
}
protected void onDraw(Canvas canvas)
{
Paint paint = new Paint();
setImageResource(R.drawable.board);
paint.setColor(Color.BLUE);
canvas.drawText(x.getName(), x.getX(), x.getY(), paint);
}
}

You should call the super.onDraw in your onDraw method before your draw code.

Related

StaticLayout getHeight always return line count

I need to draw some text on canvas, this text may single line or multi lines. I found StaticLayout can fill this require. But When I create an StaticLayout and after I want to draw it, I call getHeight(), I found it always return the line count. Shouldn't this function return the number of pixels?
This is my code:
m_staticLayout = new StaticLayout(m_message, textPaint, m_messageWidth,
Layout.Alignment.ALIGN_NORMAL, 1.0f, 0f, false);
Any help will be appreciated.
Firstly, StaticLayout is deprecated.
The reason it probably doesn't return pixels is because we haven't drawn anything yet, we're just initializing the StaticLayout. Hence, it returns the line count which we could probably use in the future. If you are trying to draw some text on Canvas, I wouldn't recommend using StaticLayout.
Instead, use the Paint class, Canvas, and Bitmap. Think of paint as the ink of the Canvas(which hosts all the draw calls). Canvas will draw into your Bitmap.
We will have to create the Paint, set up it's attributes, and then host the draw call drawText to the canvas. The Canvas will then draw the text using the Paint we created.
All of this will be in an Activity which extends View, which we will then pass as the View in setContentView for our MainActivity
This is how we can implement this:
MainActivity.java:
public class MainActivity extends AppCompatActivity {
OtherActivity otherActivity;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
otherActivity = new OtherActivity(this);
otherActivity.setBackgroundColor(Color.GRAY);
setContentView(otherActivity);
}
}
OtherActivity.java:
public class OtherActivity extends View {
public OtherActivity(Context context) {
super(context);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(Color.BLACK);
paint.setTextSize(20);
canvas.drawText("Some Text", 10, 25, paint);
}
}

How to add textview to dynamic surfaceview android

Actually my problem is I want to add text view to surface view at a particular position whether it may be corner or centre.In this I am getting surface view dynamically and I have to add text view to this surface view dynamically please help me
Another approach would be to write the text directly into the SurfaceView. To do this, you can create your custom implementation of SurfaceView by extending it. Then, rewrite the onDraw() method to draw your text on top of it.
Haven't tested to see if this works, but trye something like:
public class MySurfaceView extends SurfaceView {
Paint paint;
public MySurfaceView() {
Paint paint = new Paint();
paint.setColor(Color.BLACK);
paint.setTextSize(25);
setWillNotDraw(false);
}
public class onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawText("Your Text", 10, 10, paint);
}
}

How can I draw text to a view in a circular pattern in Android

I want to add text in a circle or half circle programmatically, in such a way that instead of having a circle with line edges, the edges are the words. See image for a better explanation.
How can I do this in Android, or what resources could I read in order to help me with this problem?
In order to do this, you will need to draw your text onto a Canvas. Any subclass of View is passed a Canvas in onDraw() that you can use to draw your custom text. The method drawTextOnPath() lets you put text on any Path object you choose. You can create a semi-circle path by creating a new instance and using addArc().
you can Use Below Code. and Make it as you Want your Textview.
Here if you want Something as Backgroung image then use setBackgroundResource(R.drawable.YOUR_IMAGE);
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new GraphicsView(this));}
static public class GraphicsView extends View {
private static final String QUOTE = "text in a half-circle";
private Path circle;
private Paint cPaint;
private Paint tPaint;
public GraphicsView(Context context) {
super(context);
int color = Color.argb(127, 255, 0, 255);
circle = new Path();
circle.addCircle(230, 350, 150, Direction.CW);
cPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
cPaint.setStyle(Paint.Style.STROKE);
cPaint.setColor(Color.LTGRAY);
cPaint.setStrokeWidth(3);
// For Background Image
setBackgroundResource(R.drawable.YOUR_IMAGE);
tPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
tPaint.setStyle(Paint.Style.FILL_AND_STROKE);
//TextColor you want to set
tPaint.setColor(Color.BLACK);
//TextSize you want to set
tPaint.setTextSize(50);}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawTextOnPath(QUOTE, circle, 485, 20, tPaint);}
}
}
try it out. hope it will help you.

Is there a way to extract a Canvas or Bitmap from a View?

I have this class that extends View and draws a line:
public class MyDraw extends View
{
Paint paint = new Paint();
public MyDraw(Context context)
{
super(context);
paint.setColor(Color.BLUE);
}
#Override
public void onDraw(Canvas canvas)
{
super.onDraw(canvas);
canvas.drawLine(1, 1, 100, 100, paint);
}
}
I would like to use the existing view from the Context to draw on top of it. Is it possible?
If you are just trying to get the view as a bitmap, you can get it from the drawing cache. This should work.
view.buildDrawingCache;
Bitmap bm = view.getDrawingCache
You cannot use the exisitng view instance and add it again as it already has a parent assigned to it and it wil cause an exception.

How to take canvas on imageview in android

I want to display canvas contents on imageview in android
i am not understanding the
imageview.draw(canvas);
Heres my code:
public class Matrix extends Activity {
public Bitmap mybitmap,newbmp,bitmap,bmp;
ImageView imageview;
Paint paint;
#Override
public void onCreate(final Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
imageview=(ImageView)findViewById(R.id.ImageView01);
imageview.setDrawingCacheEnabled(true);
}
protected void onDraw(Canvas canvas)
{
imageview.draw(canvas);
mybitmap=BitmapFactory.decodeResource(getResources(), R.drawable.image);
canvas.drawBitmap(mybitmap, 0, 0, paint);
}
}
"I want to display canvas contents on imageview in android"
So you want to draw what is on the Canvas in to your ImageView? If that's what you want then you need to read the links given by johike because you seem to have become confused a little.
The following in your code:
imageview.draw(canvas);
Does NOT mean draw the contents of canvas in to the imageview. It means the opposite, draw the imageview to the canvas.
Even if your question is not detailed enough to give you a precise answer I can give you the following hints:
Derive your on class from ImageView and then override the onDraw method
#Override
protected void onDraw(Canvas canvas) {
// draw a blue background
canvas.drawColor(Color.BLUE);
// additional drawings here
}
Further study the Android references:
http://developer.android.com/guide/topics/graphics/2d-graphics.html
http://developer.android.com/reference/android/graphics/Canvas.html

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