I try to emulate the look of a themed noneditable combobox (CBS_DROPDOWNLIST) using DrawThemeBackground. I supply the part CP_READONLY, which apparently draws the background of a themed combobox:
DrawThemeBackground(theme, dc, CP_READONLY, CBRO_NORMAL, &rectangle, nullptr);
However, it does not contain the dropdown arrow. So, I tried to paint the arrow myself the following way:
rectangle.left = rectangle.right - 20;
DrawThemeBackground(theme, dc, CP_DROPDOWNBUTTONRIGHT, CBXSR_NORMAL, &rectangle, nullptr);
But the above draws the arrow centered within the rectangle on a combobox background including the border, so I cannot use this without having a border within the combobox (which itself already has a border). I used theme-explorer to verify that the arrow is always on a background with borders.
In essence, my question is: How can I draw the background and the arrow at the appropriate position to emulate the look of a plain windows combobox?
What I have found out so far:
I can specify a clipping rectangle to clip away the aforementioned borders. But this poses the question of determining the exact position rectangle and the clipping rectangle: It seems that I can use GetThemeMargins to determine the margins, but that does not tell me how large the arrow is as a whole.
GetThemeBitmap might be useful in determining the exact size of the arrow, but as I read here and confirmed on my machine, using it with TMT_GLYPHDIBDATA does not work as advertised, and I would like to go without any workarounds, if possible.
Related
Say you have a form that you can expand to the left to show additional controls:
Collapsed:
Expanded:
The simplest way to achieve this in Delphi is to use alRight as the primary anchor for all controls (instead of alLeft) and then simply adjust the width and X coordinate of the form. Either you can set the Width and Left properties individually, or you can use a function that sets them simultaneously, like
if FCollapsed then
SetWindowPos(Handle, 0, Left - Width, Top, 2 * Width, Height, 0)
else
SetWindowPos(Handle, 0, Left + Width div 2, Top, Width div 2, Height, 0)
The problem is that there is quite noticeable flickering in the always-visible part of the form (in this example, the buttons) while expanding or collapsing. Try it yourself!
It is possible for the operating system to resize the form to the left without any flickering at all -- just grab the left edge of the form using the mouse and drag the mouse to the left or right -- but I am unable to find any function in the Windows API that exposes this kind of resizing.
I have tried to use several different Windows API functions to resize and reposition the form, tried their various parameters (for instance, the SWP_* flags), tried LockWindowUpdate, WM_SETREDRAW, TForm.DoubleBuffered etc. to no avail. I also examined the possibility to use the WM_SYSCOMMAND SC_SIZE approach.
I am not yet sure if the problem lies at the OS level or the VCL level.
Any suggestions?
Edit: I am very surprised to see that this Q received close votes. Let me try to clarify:
Create a new VCL forms application.
Add a few buttons to the right side of the main form and a memo to the left. Set Anchors to [alTop, alRight] on all controls. On the OnClick handler of the buttons, add the following code:
if FCollapsed then
SetWindowPos(Handle, 0, Left - Width, Top, 2 * Width, Height, 0)
else
SetWindowPos(Handle, 0, Left + Width div 2, Top, Width div 2, Height, 0);
FCollapsed := not FCollapsed;
where FCollapsed is private boolean field of the form (initialized to false).
Now, click the buttons repeatedly. (Or give one of them keyboard focus and hold the Enter key for a few seconds.) You will probably notice that the region with the buttons on your monitor will not display a perfect still image, but will flicker. In addition, you might actually see 'ghosts' of the buttons to the left of the actual column of buttons.
I am unable to capture this millisecond flickering using screen capture, so instead I used a digital camera to record my screen:
https://privat.rejbrand.se/VCLFormExpandFlicker.mp4
In this video clip, it is apparent that the column of buttons isn't a static image on the screen; instead, for a few milliseconds each time the form is resized, this region is something else than it should be. It is equally apparent that there is a 'ghost' column of buttons to the left.
My question is if there is any reasonably simple way to get rid of these visual artefacts (that at least to me are very visible even if you expand/collapse the form a single time).
On my Windows 10/Delphi 10.1 computer at work, the form is resized in a perfect manner when I drag its left-most edge using the mouse: the unaffected client area of the form is perfectly static on the monitor. However, on my Windows 7/Delphi 2009 PC at home, I do see that there is a lot of repositioning going on when I do this.
I can provide some insight about why you see ghost images of the other half of your UI and possibly a way to stop it. The ghost image indicates that someone is copying your client area pixels (and copying them to the wrong place, always flush-left in your window) before you have a chance to redraw them with the correct pixels.
There are likely two different, overlapping sources of these ghost pixels.
The first layer applies to all Windows OSes and comes from a BitBlt inside SetWindowPos. You can get rid of that BitBlt in several ways. You can create your own custom implementation of WM_NCCALCSIZE to tell Windows to blit nothing (or to blit one pixel on top of itself), or alternately you can intercept WM_WINDOWPOSCHANGING (first passing it onto DefWindowProc) and set WINDOWPOS.flags |= SWP_NOCOPYBITS, which disables the BitBlt inside the internal call to SetWindowPos() that Windows makes during window resizing. This has the same eventual effect of skipping the BitBlt.
However, Windows 8/10 aero adds another, more troublesome layer. Apps now draw into an offscreen buffer which is then composited by the new, evil DWM.exe window manager. And it turns out DWM.exe will sometimes do its own BitBlt type operation on top of the one already done by the legacy XP/Vista/7 code. And stopping DWM from doing its blit is much harder; so far I have not seen any complete solutions.
For sample code that will break through the XP/Vista/7 layer and at least improve the performance of the 8/10 layer, please see:
How to smooth ugly jitter/flicker/jumping when resizing windows, especially dragging left/top border (Win 7-10; bg, bitblt and DWM)?
Since you have multiple child windows, the situation is even a little more complicated. The BitBlt type operations I mentioned above happen on your whole top-level window as a whole (they treat the window as one set of pixels regardless of how many windows are underneath, and regardless of CLIPCHILDREN). But you need to have windows move atomically so that on the next redraw they are all positioned correctly. You may find BeginDeferWindowPos/DeferWindowPos/EndDeferWindowPos useful for that (but only go there if the above tricks do not work).
Effect like the mac mail app,this image is a screenshot
how can i get effect like that. I try the cocoa text system,and don't find some useful things.
and I use the nstextattachment with textatttachmentcell initImageCell,obtain some effect like that,but it is not good,it is not very nature.
please some one give directions to me.
Those objects are not glyphs, they are controls, such as a subclass of a button. Custom controls have a drawing routine, which you override to draw a blue rectangle with round corners (a bezier path is the most flexible way to do so), then you draw the text (including the caret character) centered in the blue rectangle. Finally, handle the mouse events to do what you need to do when the control is clicked, such as popping up a menu in the right location.
I am implementing a border control in win32, and I have implemented various styles for that border. I am using simple MoveTo() and LineTo() commands for drawing the border.
My problem is, when i select some new style for my border, it starts painting over the currently drawn border. I understand i need to refresh/repaint my window inorder to have a fresh canvas. I am using InvalidateRect() for now to achieve this purpose. But I am concerned, If i have other windows associated with my border control window (as child windows), how will this effect the child windows?i will need to repaint everything on this window, correct?
Secondly, Is there anyway I can draw lines inside a GDI Region (HRGN)? So far, all i have come across is how to fill up that HRGN with some fill color. Is there anyway i can retrieve HDC associated with that particular HRGN object??
This is not a concern, anything you draw is automatically clipped by the child window rectangles. No extra code is required. The underlying window style flag is WS_CLIPCHILDREN.
You cannot draw lines in a region nor are they associated with a device context. Other than by drawing the region and then drawing the lines in your paint message handler. You are probably interested in paths. The MSDN docs start here.
My goal is to draw a Group Box that is not rectangular but instead has the corners cut away. I do not mean just clipping the corners, but rather have a continuous closed path where the corners are "indented." I want this to match the colors/style of the current theme.
I noticed on Windows XP that the Group Box has 1-pixel gray lines, but on Windows 7 there is a 3D effect created by having a gray line next to a white line (the white line on the interior except on the bottom where it's below the gray line).
You can get the color of the text label of a Group Box using something like this:
COLORREF cref;
GetThemeColor(hTheme, BP_GROUPBOX, GBS_NORMAL, TMT_TEXTCOLOR, &cref);
So, I'm trying to figure out how to get the color(s) and/or properties of the lines used in a Group Box, then (I hope to) be able to draw the lines I want matching the Group Box style by separately drawing each piece of the shape I want. I'm not sure what properties are used to describe the lines or if functions line DrawRect will draw the 3D effect with a suitable Pen. Is there a way to set a Pen to draw these 3D effects (2-shade parallel lines)?
Thanks.
The thing I always find unexpected about groupboxes is that they are really a style of buttons. (BS_GROUPBOX).
Themed groupboxes (XP and later with classic mode off) use theme part BP_GROUPBOX in VSCLASS_BUTTON. You can use the usual theme APIs to get and draw. If your Group box needs text you can use DrawThemeText.
There are APIs for drawing non-themed group boxes too (e.g. DrawEdge), but I don't remember the details and it's unlikely that you need them.
As usual, I will point out that reproducing the behaviour of controls is always harder than you think it is going to be.
Martyn
i've created a layered window by adding the the WS_EX_LAYERED extended style:
wndClass.ExStyle = wndClass.ExStyle | WS_EX_LAYERED;
Windows will use black as the chroma key color value. i'm going to leave a large border of black to make the problem obvious:
After the window is constructed, i tell it to use black as a chroma-key color:
SetLayeredWindowAttributes(hwnd, 0x00000000, 255, LWA_COLORKEY);
Now the popup layered window appears partially transparent:
The problem is the final step. i want to use CS_DROPSHADOW class style, available since Windows XP, to create a drop-shadow:
wndClass.Style = wndClass.Style | CS_DROPSHADOW;
The drop shadow appears, but the shadow surrounds the original rectangular window, and doesn't take into account the window's transparency provided by the layered window:
Does anyone know what magical option i've missed somewhere that will make the drop shadow honor the non-rectangular layered window?
Another example of where this issue appears is when you don't include the 6px padding/margin. The hint window as drawn by Windows® themes is non-rectangular. This leaves a small visible gap where the window is transparent, but the drop shadow does not appear:
Microsoft has managed to make it work, as you can see from this hint from Internet Explorer:
Looking closer at a Windows tooltips class hint window. Using SpyXX - i can get its window rect, and class styles:
SpyXX says:
Rectangle: (440, 229)-(544, 249), 104x20
Restored Rect: (440, 229)-(544, 249), 104x20
Client Rect: (0, 0)-(104, 20), 104x20
So everything points to the window itself being 104x20 pixels, with the drop shadow outside the window itself. (Which is consistent with CS_DROPSHADOW.)
Next i can look at the styles of the tooltips window class:
Windows Styles: 94000001
WS_POPUP 80000000
WS_VISIBLE 10000000
WS_CLIPSIBLINGS 4000000
TTS_ALWAYSTIP 1
Extended Styles: 00080088
WS_EX_LAYERED 80000
WS_EX_TOOLWIN 80
WS_EX_TOPMOST 8
Interestingly, it doesn't use CS_SAVEBITS (0x800); which is useful for small, short-lived, windows.
Nor does it use CS_DROPSHADOW (0x20000). So now i wonder how is it drawing outside its own window?
Note: Transparent layered windows is documented as the preferred technique over regions.
Edit: Layered Windows have been around with Windows 2000. CS_DropShadow was added with XP.
Transparent layered windows is documented as the preferred technique over regions.
However, CS_DROPSHADOW does pay attention to regions. If you crop or otherwise shape your window using a region, the drop-shadow will follow the new outline.
Fortunately, you can use regions with layered windows, and by combining the two get the effect you're looking for.
BTW: tooltips_class32 does use CS_DROPSHADOW - you won't see it in the window styles because it's a class style, not a window style.
Why don't you use LWA_ALPHA and build the shadow into the image?
Edit in reponse to your comment:
A) Doesn't stop you using an alpha channeled PNG for a shadow only. Blt the 2 images together and use as one single image.
B) Its not hard to generate a drop shadow. In the image you posted its black with 3 different alpha values.
C) But it doesn't work does it? ie Time to get creative.
D) Then don't try and get windows to do something it won't do for you.
E) Is entirely irrelevant. Layered windows handle that for you.
I strongly recommend you learn more about layered windows because they CAN help you to your goal.
Edit2: You have the bitmap. Its fairly easy to scan over the image and find which bits will be colour keyed (by identifying the black yourself) and hen modify that to have an alpha of 0 where everything else will have an alpha of 255 (Not: You may have to convert the image to a 32-bit image from a lower colour format, you can do this by creating a new DC and copying the image). This will give you the same effect with LWA_ALPHA as with LWA_COLORKEY. From there its fairly easy to identify the pixel at the edge, where the color changes to (R = 0, G = 0, B = 0, A = 0). You then change that first pixel to have a n alpha of 192, the one blow it to 128 and the one below to 64. You now have an alpha'd gradation below the image that will look like the shadow. You can adjust the alpha to get the effect you want.
CS_DROPSHADOW only works with standard rectangular windows. WS_EX_LAYERED windows don't support everything. They are more of a low-level, self-service method to draw exactly what you want.
To get a drop shadow, you'll have to generate the drop-shadow yourself from the alpha channel in the image.