I have a MFC application where I have a Picture Control in the dialog. Eventually, I want to allow a user to draw a resizeable rectangle via mouse drag in the picture control over an image that I loaded.
I defined my own picture control class as a sub class of CStatic and am working with the mouse down, mouse up, and mouse move events but I can't seem to figure out how to allow the user to draw a rectangle. Any guidance on this would be appreciated.
Most of the examples I've looked at show me how to draw a rectangle in a CView:CWnd, but I'm not too familiar with MFC yet so I'm a bit lost. Thanks.
The usual technique for drawing a drag rect on top of the window contents is illustrated here:
http://msdn.microsoft.com/en-us/library/windows/desktop/dd145184(v=vs.85).aspx
That is Win32 API coding instead of MFC coding but the differences are minimal. The basic idea is that by drawing with SetROP2(hdc, R2_NOTXORPEN); you invert the existing pixels, then drawing the same rect again re-inverts those pixels back to the original image.
When the user clicks the mouse button you need to record the mouse coordinates so you know where the rectangle starts. You should also set some type of flag to indicate that the user is dragging the mouse. When the user moves the mouse get the current mouse position and use DrawDragRect or similar function to draw the rectangle. When the user releases the mouse button clear the previously mentioned "flag" and you're done with that part of the process.
You will also need to handle other events such as the control and/or parent window losing focus so that you can cancel the drag/draw operation. Since you did not include any code in your question it's hard to say what else you will need to do but those are the basics.
Related
I need to know if there is a code in c++ that allows to simulate a click, on a background window (if that's impossible, a foreground window will do fine), without moving the mouse.
I also need to click on specific coordinates, and drag an item to some other position (always without moving the mouse).
Example:
my mouse pointer is at (500,700),
but i need to left click at (100,150),
and drag to (700,300).
I need to be able to move my mouse pointer without affecting the program,
and the program must run correctly without moving, or locking, the mouse pointer.
If this action is impossible in c++, a VB code will be apreciated.
From a C++ Windows application, you can call Windows API directly by first finding the window using FindWindow that will give you the window handle you want, then finding the area within this window that you want to click. You can use API like GetWindowRect for this.
Finally, you can send this window, or an area within it, mouse messages using mouse_event function to cause the mouse to move, click, drag and let go at a new location.
I need to draw an icon that moves approximately in sync with mouse cursor and is always on top of all windows.
OS: Windows 7
I have a solutions that work to some extend by drawing my icon in a top most transparent window. There are some major drawbacks in this solution since that top most window interferes with other top most windows and some full screen apps do not work correctly. Examples are start menu and task bar that will overlay my window if I do not regulary set it to be top most. For some full screen applications performance of updating position of window with icon hugely drops and it does not follow mouse smoothly.
There is another method that I came across where an icon is drawn directly to the device context of desktop Draw mouse pointer icon?. This solution has a drawback that there seems to be no good way of how to remove "trail", especially if desktop content changes quickly.
So my question: is there an ultimate solution that does not have the above mentioned problems?
Is it possible to draw above all windows in the "layer" of mouse cursor? Or make a second mouse cursor with my custom icon that I will control (I know that widows can display two independently controlled mouse cursors like CPNMouse)?
Can someone point me to the right direction?
Thanks!
Use a top-most window with transparency set via WS_EX_LAYERED / UpdateLayeredWindow.
If you set the WS_EX_TRANSPARENT style as well then the window won't intercept mouse input.
https://stackoverflow.com/questions/9466359/graphics-editor-in-c
I've developed a simple graphics editor in c++.It requires me to drag the mouse to draw a shape .After drawing the shape I want to fill it by picking a color but since dragging the mouse amounts to a large number of clicks because of which the entire screen gets filled with a default color even before i've drawn the shape. delay() doesn't work either.
the mouse click event in turbo c++ has two part. one where you press the button and two when you release the button. you need to drag so you should use the clrscr() function in the loop which goes on iterating until the mouse button is pressed down along with the code for the shape you want to draw. that way your screen keeps getting updated when you are dragging the mouse. and the loop ends when you release the button.
for filling the shape using the flood fill function should suffice
Perhaps one of the following links is what you're looking for:
http://www.codeproject.com/Articles/11313/Mouse-Programming-in-C-C
http://www.cprogrammingreference.com/Tutorials/Advance_Tutorials/mouseprogramming.php
http://www.brackeen.com/vga/mouse.html
This is my first attempt at writing a QT app, and I'm just trying to get a feel for how it works. My goal is to have a 400x400 widget which knows the exact position of the mouse when the mouse is hovering over it. For example, if the mouse was hovering in the top left corner, the position might be 10,10 (or something similar). If the mouse is in the bottom right corner, it might say 390,390.
Eventually, these coordinates will be displayed in a label on the main window, but that should be trivial. I'm stuck at the actual fetching of the coordinates. Any ideas?
For your widget, you must enable mouse tracking.
Then, you can either install an event filter, paying attention to mouse events and looking for the move event, or you can inherit from QWidget and override the mouse event, looking for mouse move events.
http://doc.qt.io/qt-4.8/qwidget.html#mouseTracking-prop
http://doc.qt.io/qt-4.8/eventsandfilters.html
http://doc.qt.io/qt-4.8/qmouseevent.html
If you are ever in a situation when you don't need actual tracking, just position at the moment, you can use QCursor::pos().
I seeking solution for Windows first.
I need to add visual effects to screen image without breaking the interactivity of all and every controls, that are on this screen.
The solution can be straightforward:
1. take a screenshot
2. show this screenshot in a separate window, above other windows
3. apply the effect to image, being shown on this window
But, this window (containing screenshot) makes any buttons and other controls below, unreachable for mouse interaction (clicking, hovering)
Is there any way to do this ?
From MSDN's documentation on layered windows...
"Hit testing of a layered window is based on the shape and transparency of the window. This means that the areas of the window that are color-keyed or whose alpha value is zero will let the mouse messages through. However, if the layered window has the WS_EX_TRANSPARENT extended window style, the shape of the layered window will be ignored and the mouse events will be passed to other windows underneath the layered window."
Here's an article about it. Notice this additional warning:
"setting the WS_EX_TRANSPARENT attribute affects the entire window: the user can't close the window using the 'x' button, select it with the mouse, or select any controls on the window. The application can still close the window programmatically."
Depending on what you're actually drawing and where, it might be more appropriate to use Owner-Drawn Controls rather than hover an "onion skin" over your whole window.