How to implement Hittest on png's

Question

1.00/5 (1 vote)

See more:

hi all:-)

I have Cwnd in which i draw a .png-file. (First i convert it to a CBitmap, then i draw it)

Now i need a hittest-function: If a user clicks on the png-Image, is there a way to find the pixel, he clicked on?

What would help me too:

If there is for example a circle in the png, is there a way to find the area of this circle in screen-coordinates, or is there a method to find, if a click on the png-image was inside this circle?

thx for any help!

Posted 19-Feb-15 20:29pm

Member 10781325

Add a Solution

Comments

Sergey Alexandrovich Kryukov 20-Feb-15 3:03am

Wrong approach, I would say. Why doing so?
—SA

Member 10781325 20-Feb-15 3:14am

i am just searching a way of knowing, where to user did the click in the png-image. Do you have an idea, or an approach to achieve this?

What i have is a picture with several enclosed areas. Now i want to invoke different functions, depending on which area the user clicked on.

Richard MacCutchan 20-Feb-15 3:53am

You can use one of the various mouse messages/notifications to find the pixel that was clicked; that part is easy. However, image analysis is far more complex, since you have to account for shading and colour blending. Use Google to find one of the libraries that deal with the subject.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

KarstenK · Accepted Answer · 2015-02-19T21:56:00

Solution 1

You must handle the mouse messages. For that you must overwrite the message handler in your window. Here is the Microsoft documentation for the mouse messages. You must fetch the click coordinates and than check it with the coordinates of your picture.

Posted 19-Feb-15 21:56pm

KarstenK

Comments

Member 10781325 20-Feb-15 7:09am

yes, thanks all! i found a way: mouse Messages-> coordinates of click. With this, i can find the Pixel which was clicked. When i create the Picture, i hold a second Bitmap in the Background (not drawn, but same size), whose Pixels tell me, in which Region the click was. (e.g. red Pixels mean in Region 1, black Pixels in Region 2 and so on)