Develop Reference

Java - Screen Coordinates to Image Coordinates

I am using a Java application to display an image on the screen. I also am using an eye-tracker device which records the absolute pixel X,Y locations where the person is looking on the screen.
However, what I need to do is convert these X,Y coordinates from the screen positions into the X,Y locations of the image. In other words, somehow I need to figure out that (just an example) 482, 458 translates to pixel 1,1 (the upper left pixel) of the image.
How can I determine the image's placement on the screen (not relative to anything)?
I saw a few posts about "getComponentLocation" and some other APIs, but in my experimentation with these, they seem to be giving coordinates relative to the window. I have also had problems with that because the 1,1 coordinate that they give is within the window, and there is actually a bar at the top of the window (that has the title and the close and minimize buttons) whose width I do not know, so I cannot easily translate.
Surely there must be a way to get the absolute pixel location on the screen of a component?

If we are talking about Swing/AWT application than class java.awt.Component has method getLocationOnScreen which seemed to do what you want
And yes as #RealSkeptic mentioned in comments to question:
SwingUtilities.html#convertPointFromScreen
will do all this work for you considering components hierarchy

render what's goes outside of the screen in 2d

how can I render whats right outside of the screen on the left side? Like in Super Mario Bros for example? I want to move clouds endless over the screen.
Here's an example of what I mean:
http://image-upload.de/file/nSzNhe/612a71bf0d.png

You simply create the entity with coordinates that are offscreen, and have a draw function that draws the entities, and when they move onscreen, they will be drawn. Might also want to make sure they get deleted once the go offscreen again though.

Get portion of an image using rotated Shape

From the above image if I want a portion behind the RED Rectangle I can easily get it,
but the issue I cannot get the portion behind the Yellow Rectangle because it is rotated.
So how can I get a portion of an image from a rotated shape on it?
For example my goal is to get a portion of an Image where the rectangle is located on the image. if someone rotates this rectangle by an x degree [in whatever direction] then it is getting difficult to extract the exact portion of an image after applying rotation.
Any suggestions?

Here a more lengthy description of a possible approach. I do not know the Java2D drawing API very well but if I remember correctly it has the capabilities to do what is required.
First you have to figure out the translation and rotation of the subregion you want compared to an equally size rectangle located straight in the upper left corner in the image. Then invert this transformation.
Make a graphics context which is backed by a bitmap in memory. This one should have the size of the subimage you want. Setup the inverse transformation you calculated earlier on the context and draw your image at position 0,0. As Java2D will take the transformation into account you should now get the sub image you want in the memory bitmap.

Mihir, I think you might be getting distracted by the rotation/AffineTransform aspects of this challenge and it is leading you down the wrong road. Also keep in mind that I don't totally know what you mean by "get" here -- do you want to save out the highlighted region to an image? Do you want to render it as a watermark on another image? etc... I'll just try and answer in the general case to get you down the right track.
What you want is the content from the image defined by the polygon in yellow in your image above; ignoring the fact that it looks like a rotated rectangle.
It is late and I am missing a step in here, but I think this will get you 90% of the way there and clarify the last piece (Graphics2D.setClip) that you need.
Create a java.awt.Polygon that defines the region around the area you want.
Use getBounds() or getBounds2D() to get the width/height of the bounding box required to hold this Polygon when rendered out into a rectangle. (e.g. boundingBox)
Create a new BufferedImage with these width/height values.
Get the Graphics2D from the new BufferedImage (e.g. newG2)
newG2.drawImage(originalImage, boundingBox.x, boundingBox.y, boundingBox.width, boundingBox.height)
NOTE This is where my memory is failing me; at some point you need to set the clip on newG2 (newG2.setClip(someShape)) so when the bounding box is rendered into it, you don't get the full bounding box of graphics rendered in, but instead some subset as defined by the yellow outline.
One easy way to do this is to create two Polygon's:
poly1 = a java.awt.Polygon that defines the yellow selection in the ORIGINAL image.
poly2 = a java.awt.Polygon that defines the exact same shape of Polygon, but shifted to a 0,0 origin point.
poly1 is used to get the bounding box to copy out the full bounding box that encompasses the content selected in yellow (and extra content around it)
poly2 is used to set the clip on the target Graphics2D (newG2) so when the bounding box is rendered into it, we clip back out everything outside of that Yellow shape so we just get the content in Yellow. You'll likely want to use an ARGB image type and set the background of the target image as transparent otherwise you'll get a black fill color.
I think this is the right direction for the clips; I was up to my eyeballs in Java2D for years and years but have been out of it for a while and forget if this will give you exactly what you want or not; you might need to tweak it around, but these are all the tools you need.

How to change the position of a view?

I have two views called x and y they are both black lines (for example I made the height of the x line is 1dp and width 230dp and as background filled with the color black).
Now i want to move the position of the lines programmatically (for example I want the y line 50dp to the right of the orginal position).
Can someone help me how to do this?
I have tried things such as setpadding but the line doesn't move.
Thanks in advance!
(ps: my minimum sdk is set for 7 so i can't use the newest api's).

Old Answer
Have a look at the Absolute Layout, it allows you to position
child elements using x, y coordinates. It is deprecated but it's the
only way in Android to do real x,y coordinate positioning.
I would ask what the main point behind what you are trying to do is
though? It sounds like you started with a goal, were led down a path
and now are asking how to get to the end of that path, rather than
asking how to do what you need to do.
Edited
For drawing graphs have a look instead at https://stackoverflow.com/questions/2271248/how-to-draw-charts-in-android.
Using a Layout class to draw a chart will only lead to a really slow app, since the layout classes are designed for creating relatively static layouts, not drawing full graphics.
Instead use either the Canvas and draw your drawables yourself or use the graphing packages listed in the SO question I linked above.

Mouse Dragging problem

i'm having the problem of capturing all the coordinate value of pixels while dragging with the mouse using mousedragged event in java
while i'm dragging slowly i'm able to get all the coordinate value of pixels
but when i'm doing it fast i'm getting only one third of the pixel coordinate values
for example if i drag it slowly i'm getting 760 pixel values but when i'm doing it fast i'm getting only 60 pixel coordinate values
please help me
I need all the points because i'm going to use all those points for the signature comparision...
Project Description :
User will put the sign using mouse in log in page, this sign will be compared with the sign which the user already put in sign up page...
I'm going to compare the sign using the pixel values, so by getting all the coordinate values only i can compare the sign...
pls help me...

Windows is not going to give you this, its up to the refresh rate of the Mouse, its DPI and the rate at which windows polls for the Mouse event. You are not going to get all pixels so you will need to make room for some ambiguity.
(It doesn't matter which language you use Java or C#)

Mouse movement events occur every few milliseconds, not for every pixel movement, so when the mouse is moving rapidly, some pixels will be missed out. If you want every single pixel, you'll have to interpolate between pixels if the new location is not adjacent to the previous one. One way to interpolate the pixels between two coordinates is Bresenham's line algorithm: http://en.wikipedia.org/wiki/Bresenhams_line_algorithm
Edit: Fixed link.