Class TCastleFloatSlider

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An easy way to construct float slider.

This item has no description. Showing description inherited from TCastleUserInterface.Render.

Render a control. Called only when Exists and render context is initialized.

Do not call this method. It will be automatically called by the engine when needed. It will be called when UI is part of TCastleContainer.Controls list or rendered (e.g. for off-screen rendering) by TCastleContainer.RenderControl.

You should only override this method.

See https://castle-engine.io/manual_2d_ui_custom_drawn.php for examples what you can put here.

You can depend on some OpenGL state being set before calling this method. You can depend on it being set, and you can carelessly change it. This state we set:

• Viewport is set to include whole container.

• Depth test is off.

• For ancient fixed-function pipeline (see TGLFeatures.RequestCapabilities):

  • The 2D orthographic projection is always set at the beginning. Useful for 2D controls.

  • The modelview matrix is set to identity. The matrix mode is always modelview.

  • The raster position is set to (0,0). The (deprecated) WindowPos is also set to (0,0).

  • Texturing, lighting, fog is off.

Beware that GLSL RenderContext.CurrentProgram has undefined value when this is called. You should always set it, before making direct OpenGL drawing calls (all the engine drawing routines do it already, this is only a concern if you make direct OpenGL / OpenGLES calls).

This item has no description. Showing description inherited from TCastleUserInterface.Press.

Override this method to react to user pressing a key, mouse button or mouse wheel. Return True if the event was handled, which prevents from passing this event to other UI controls.

When implementing in descendants it is best to override it like this:

function TMyControl.Press(const Event: TInputPressRelease): boolean;
begin
  Result := inherited;
  if Result then Exit; // exit if ancestor already handled this event

  if Event.IsKey(keyEnter) then
  begin
    // do something in reaction to Enter key
    ...
    // let engine know that this input event was handled
    Exit(true);
  end;

  if Event.IsMouseButton(buttonLeft) then
  begin
    // do something in reaction to left mouse button press
    ...
    // let engine know that this input event was handled
    Exit(true);
  end;
end;

These events are generated for all UI controls, whether they are considered "interactive" or not. These events are generated for non-interactive controls like TCastleRectangleControl or TCastleLabel as well. For example, these events ignore the TCastleButton.Enabled state, they are generated always (see https://github.com/castle-engine/castle-engine/issues/413 ). Use instead TCastleButton.OnClick to detect clicks on a button in a way that honors the TCastleButton.Enabled state.

When a control returns True from Press, it means it starts to "capture" subsequent mouse events: subsequent mouse moves and release will be send to this control even if mouse will move outside of this control.

The events Press and Release are passed to the parent only after the children had a chance to process this event. Overriding them makes sense if you draw something that "looks clickable" in TCastleUserInterface.Render, which is the standard place you should draw stuff. For example our TCastleButton draws there.

In contrast, the events PreviewPress and PreviewRelease are passed first to the parent control, before children have a chance to process this event. In partcular, overriding them makes sense if you draw something that "looks clickable" in TCastleUserInterface.RenderOverChildren.

This item has no description. Showing description inherited from TCastleUserInterface.Motion.

Motion of mouse or touch.

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Round to multiple of MultipleOf, if non-zero, and clamp to Min and Max range.

This item has no description. Showing description inherited from TCastleComponent.PropertySections.

Section where to show property in the editor.

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Current value. Usually within Min and Max range, although the general code should be ready for handle any value here (to work even during changes to Min and Max properties).

If non-zero, we force the value selected by user to be a multiple of this value (clamped to Min, Max range). For example, if you set this to 0.25, and slider is between 0..1, then when user clicks around 0.3 — we will pick 0.25. It user clicks around 0.4 — we will pick 0.5.

This only affects values selected by user interactions (clicking, dragging). This does not process the values you set by code to Value property, though you can use RoundAndClamp method on your values yourself.