craydate 0.1.7

A safe Rust API for the Playdate hand held gaming system.
Documentation 
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use super::bitmap::BitmapRef;
use crate::capi_state::CApiState;

/// A sentinel that marks a bitmap acting as the stencil for drawing. Destroying this object will
/// unset the bitmap as the stencil.
pub struct FramebufferStencilBitmap<'a> {
  generation: usize,
  bitmap: &'a BitmapRef,
}
impl<'a> FramebufferStencilBitmap<'a> {
  pub(crate) fn new(bitmap: &'a BitmapRef) -> Self {
    // Track the generation number so as to only unset the stencil on drop if set_stencil() wasn't
    // called again since.
    let generation = CApiState::get().stencil_generation.get() + 1;
    CApiState::get().stencil_generation.set(generation);
    FramebufferStencilBitmap { generation, bitmap }
  }

  /// The bitmap that was set as the stencil when the `FramebufferStencilBitmap` was constructed.
  pub fn bitmap(&self) -> &'a BitmapRef {
    self.bitmap
  }

  pub(crate) fn fns() -> &'static craydate_sys::playdate_graphics {
    CApiState::get().cgraphics
  }
}

impl Drop for FramebufferStencilBitmap<'_> {
  fn drop(&mut self) {
    // Use a generation tag to avoid unsetting the stencil if another bitmap was set before this
    // object was dropped.
    if self.generation == CApiState::get().stencil_generation.get() {
      unsafe { Self::fns().setStencil.unwrap()(core::ptr::null_mut()) }
    }
  }
}