Off-screen Regions and High-DPI Displays

Rendering to a texture

RmlRegion.make() accepts any GraphicsOutput, so an interface can be rendered into a texture buffer and shown on a model: a terminal on a monitor, a control panel on a machine. The samples/rocket-console sample does exactly this.

buffer = base.win.makeTextureBuffer("console", 1024, 512)
texture = buffer.getTexture()
screen_model.setTexture(texture, 1)

region = RmlRegion.make("console", buffer)
region.set_input_handler(handler)
context = region.get_context()
context.load_font_face("fonts/dos437.ttf")
context.load_document("ui/console.rml").show()

The buffer renders before the window, so the texture is current when the model draws. The context’s size is the buffer’s size.

High-DPI displays

RmlUi lays out in density-independent pixels, dp, scaled by the context’s density-independent pixel ratio. When a window opens on a high-DPI display with dpi-aware enabled, the framebuffer has more pixels than the logical size that was requested; the region detects this and sets the ratio so that dp sizes – fonts, layout – keep their intended physical size while text is rasterised at native resolution. Override it with RmlContext.set_density_independent_pixel_ratio() to scale an interface up or down deliberately.

Media queries work with the same scale: @media (max-width: 800dp) is evaluated in dp, ratio included, so a breakpoint written once behaves the same on every display. Element geometry returned by RmlElement, on the other hand, is always in framebuffer pixels.