I have a piece of code that rely's on correctly measuring the width of the text. Most of the time, I am trying to measure the width of whitespace in current font that has been set.
While this generally works - I have seen instances in production logs that the ctx.measureText(' ').width was zero.
I did some digging around - The font size is never zero. It is always double digit in px.
I looked at the chromium codebase and it seems that the TextMetrics object is always created a new object.
Does anyone know what else could be causing this to be zero ?
I figured out why this was happening.
The font that was set in the canvas context was getting downloaded. It was not available to the browser.
Chromium code
const SimpleFontData* font_data = font.PrimaryFont();
if (!font_data)
return;
Related
I'm currently getting started with Win32 and Direct2D and reached the chapter on DPI and DIP. At the very bottom it says ID2D1RenderTarget::GetSize returns size as DIP and ID2D1RenderTarget::GetPixelSize as physical pixels. Their individual documentation confirms that.
However I cannot observe that ID2D1RenderTarget::GetSize actually returns DIP.
I tested it by
setting the scale of one of my two otherwise identical displays to 175%,
adding <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness> to my application manifest,
obtaining
D2D1_SIZE_U sizeP = pRenderTarget->GetPixelSize();
D2D1_SIZE_F size = pRenderTarget->GetSize();
in method MainWindow::CalculateLayout from this example (and printing the values),
and moving the window from one screen to the other, and arbitrarily resizing it.
I can see the window-border changing size when moving from one display to another. However, the values in both sizeP and size (besides being int and float) are always identical and correspond to the physical size of the ID2D1HwndRenderTarget.
Since I do not expect the documentation to be flawed, I wonder what I am missing to actually get the DIP of the window of the ID2D1HwndRenderTarget pRenderTarget.
The size is only relative to the DPI of the render target, set using ID2D1RenderTarget::SetDpi. This value is not automatically connected to the value provided by the display system, which can be queried using ID2D1Factory::GetDesktopDpi or GetDpiForMonitor.
Hello everyone so I've been trying to render a book page that is attached to your hand in VR (testing on oculus-go) using A-FRAME. Initially I tried using a plane and applying the text to it using the text attribute and then defining its value, alignment, font etc... Everything worked fine enough however the text gets "jagged edges" that seem to get worse the more you move your hand (which is basically impossible to not do) making it extremely bad for a long text-form such as a book page.
Then I tried exploring an alternative by using the aframe-html-shader by mayognaise. By creating an html div and using css it's the perfect solution in terms of customization, alignment and etc and when I render it, the text doesn't get any "jagged edges" anymore (since it's basically a texture).
However, it gets blurry enough that it becomes tiresome for long reads.
I've tried everything I could to increase its sharpness however it keeps being blurry which makes absolutely no sense to me.
What I've tried:
Increasing the size of the object the texture applies to and then scaling it back after the render - result: same thing...
Increasing the size of the canvas or the texture inside the aframe-html-shader.js - result: the same thing... however some of the tinkering attempts seem to trigger a "image too big (...) scaling down to 4000" (4000 something I don't recall the exact value) which seem to indicate the canvas is already being rendered at full resolution
Switching from Mayognaise aframe-html-shader.js to wildlifela fork (which already has an option of "scale" on the shader) and applying "canvasScale: 2" - result: same thing...
Using a 4000px width html element as the object to render from, increasing the font accordingly- result: same thing...
I'm out of ideas and really don't understand why I can't get good enough text out of the html shader since if the text is within an image and I use that same image as a texture, the text comes out perfectly readable.
Need some help from all the A-Frame experts and developers over here!
Thank you all in advance!
Increasing the size of the canvas or the texture inside the aframe-html-shader.js - result: the same thing... however some of the tinkering attempts seem to trigger a "image too big (...) scaling down to 4000" (4000 something I don't recall the exact value) which seem to indicate the canvas is already being rendered at full resolution
It wasn't too big. This is because textures needs to be a power of two size (e.g., 4096x4096).
The standard text component should be clearest though. A-Frame master branch has a fix to make text look clearer, might help. https://github.com/aframevr/aframe/commit/8d3f32b93633e82025b4061deb148059757a4a0f
A frequent operation in my Windows Table control, which I am reworking and moving into a DLL, is to get the height of a row. This is the maximum of
the height of text in the current font, in pixels
the current small icon height, in pixels (GetSystemMetrics(SM_CYSMICON))
the height of checkboxes, in pixels (determined on a WM_THEMECHANGED, when checkbox information is recalculated)
Calculating the text height, as far as I know, requires getting a DC, selecting the font in (and getting the SYSTEM_FONT if that's NULL), getting the text metrics, selecting the font out, and releasing the DC, all of which can error out/fail/etc. This means that virtually every function in my control can fail.
I can avoid this by storing the text height somewhere else, only calculating it when it changes. I know that text height is a property related to the DPI of the DC that GetDC(hwnd) returns. I would like my control to be DPI-agnostic because DPI awareness is per-process, not per-DLL/per-window.
At the same time, knowing when GetSystemMetrics(SM_CYSMICON) changes would also be useful.
So my questions are simple:
Is there a message that I can look for that will tell me that my DPI has changed and that I need to recalculate my text height?
Is there a message that will tell me that SM_CYSMICON has changed and that I need to recalculate everything? Is it the same one? (I know there is no reliable way to detect a GetSystemMetrics() failure (since 0 is a valid return and it does not set the last error code), so I am assuming it cannot fail with a valid parameter and am simply calling it each time I need to calculate the row height; this is just so I can queue a redraw when the value does change.) Would it also work for SM_CXSMICON?
In addition, looking back at my code, GetThemePartSize() takes a DC as well; do theme items like checkbox images scale with DPI? And if so, what messages do I look for in that case? The same one?
Alternative: is there a non-failing way to get the text height that I don't know about, given only a HWND and HFONT?
I will be happy to take a solution that was introduced in either Windows XP or Windows Vista; if there's a solution that was introduced in a newer version of Windows, then knowing about it could also be beneficial.
Thanks.
Firefox under version 28 has an issue where a path with a stroke-dashoffset property will render differently depending on the stroke-width amount. There is a known fix which is to divide stroke-dashoffset with stroke-width, but applying this across the board will mean other browsers will now display incorrectly.
https://bugzilla.mozilla.org/show_bug.cgi?id=661812
The quickest solution I can think of is is simply check for browser type and version number, but generally this seems to be regarded as a bad idea. Does anyone know a way to test the result without going down this route?
I have put together a Codepen which allows you to change the width of an animated offset, and a toggle for the fix so you can see for yourselves in different browsers. http://codepen.io/MattyBalaam/full/lGJkc
Using GWT 1.6.4, I have the following code to retrieve the dimensions of the browser window:
RootPanel panel = RootPanel.get();
int height = panel.getOffsetHeight();
int width = panel.getOffsetWidth();
Now, in the Hosted Mode browser, and in IE (but I believe the hosted mode browser uses IE, right?), this returns the correct values for both width and height. However, in FF3, width gives the correct value, but height is always zero. Can anyone explain this? Am I doing something wrong? What is the correct way to retrieve the height of the window in Firefox, and is there one method that works correctly in both IE and Firefox?
Did you try the Window.getClientHeight() and Window.getClientWidth() methods?
Check out the JavaDocs.
Using javascript, you can grab the window height with:
int height = document.body.clientHeight;
Now whether GWT gives you anyway to specify specific javascript pieces, I don't know. You may want to post in the GWT google group, which can be found at: http://groups.google.com/group/Google-Web-Toolkit?pli=1
I'm taking a wild guess here: in Firefox, in the moment you check RootPanel.get().getOffsetHeight(), it's empty and not stretching into the viewport, only horizontally.
So better use Window.getClientHeight() if you need the actual window/viewport dimensions.