Add style stack (#214)

Author: tychedelia

crates/processing_ffi/src/lib.rs

@@ -448,6 +448,60 @@ pub extern "C" fn processing_pop_matrix(graphics_id: u64) {
     error::check(|| graphics_record_command(graphics_entity, DrawCommand::PopMatrix));
 }
 
+/// Push the current style onto the style stack.
+///
+/// SAFETY:
+/// - graphics_id is a valid ID returned from graphics_create.
+/// - This is called from the same thread as init.
+#[unsafe(no_mangle)]
+pub extern "C" fn processing_push_style(graphics_id: u64) {
+    error::clear_error();
+    let graphics_entity = Entity::from_bits(graphics_id);
+    error::check(|| graphics_record_command(graphics_entity, DrawCommand::PushStyle));
+}
+
+/// Pop the most recently saved style off the style stack.
+///
+/// SAFETY:
+/// - graphics_id is a valid ID returned from graphics_create.
+/// - This is called from the same thread as init.
+#[unsafe(no_mangle)]
+pub extern "C" fn processing_pop_style(graphics_id: u64) {
+    error::clear_error();
+    let graphics_entity = Entity::from_bits(graphics_id);
+    error::check(|| graphics_record_command(graphics_entity, DrawCommand::PopStyle));
+}
+
+/// Push both the style and the transformation matrix onto their stacks.
+///
+/// SAFETY:
+/// - graphics_id is a valid ID returned from graphics_create.
+/// - This is called from the same thread as init.
+#[unsafe(no_mangle)]
+pub extern "C" fn processing_push(graphics_id: u64) {
+    error::clear_error();
+    let graphics_entity = Entity::from_bits(graphics_id);
+    error::check(|| {
+        graphics_record_command(graphics_entity, DrawCommand::PushStyle)?;
+        graphics_record_command(graphics_entity, DrawCommand::PushMatrix)
+    });
+}
+
+/// Pop both the style and the transformation matrix off their stacks.
+///
+/// SAFETY:
+/// - graphics_id is a valid ID returned from graphics_create.
+/// - This is called from the same thread as init.
+#[unsafe(no_mangle)]
+pub extern "C" fn processing_pop(graphics_id: u64) {
+    error::clear_error();
+    let graphics_entity = Entity::from_bits(graphics_id);
+    error::check(|| {
+        graphics_record_command(graphics_entity, DrawCommand::PopStyle)?;
+        graphics_record_command(graphics_entity, DrawCommand::PopMatrix)
+    });
+}
+
 /// Reset the transformation matrix to identity.
 ///
 /// SAFETY:

crates/processing_pyo3/examples/style_stack.py

@@ -0,0 +1,43 @@
+# Style Stack
+#
+# A grid of spinners. Each cell sets up its own transform and color inside
+# push()/pop(), so nothing leaks to its neighbours.
+from mewnala import *
+from math import sin
+
+GRID = 6
+t = 0.0
+
+
+def setup():
+    size(600, 600)
+
+
+def draw():
+    global t
+    background(16, 16, 20)
+
+    cell = width / GRID
+    for gy in range(GRID):
+        for gx in range(GRID):
+            spin = t + (gx + gy) * 0.4
+            pulse = 0.5 + 0.5 * sin(spin)
+
+            push()
+            translate((gx + 0.5) * cell, (gy + 0.5) * cell)
+            rotate(spin)
+
+            no_stroke()
+            fill(235, 90 + 130 * pulse, 60)
+            rect_mode(CENTER)
+            rect(0, 0, cell * (0.3 + 0.15 * pulse), cell * 0.3)
+
+            no_fill()
+            stroke(255, 255, 255, 40)
+            circle(0, 0, cell * 0.72)
+            pop()
+
+    t += 0.02
+
+
+run()

crates/processing_pyo3/src/graphics.rs

@@ -1371,6 +1371,30 @@ impl Graphics {
             .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
     }
 
+    pub fn push_style(&self) -> PyResult<()> {
+        graphics_record_command(self.entity, DrawCommand::PushStyle)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
+
+    pub fn pop_style(&self) -> PyResult<()> {
+        graphics_record_command(self.entity, DrawCommand::PopStyle)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
+
+    pub fn push(&self) -> PyResult<()> {
+        graphics_record_command(self.entity, DrawCommand::PushStyle)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))?;
+        graphics_record_command(self.entity, DrawCommand::PushMatrix)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
+
+    pub fn pop(&self) -> PyResult<()> {
+        graphics_record_command(self.entity, DrawCommand::PopStyle)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))?;
+        graphics_record_command(self.entity, DrawCommand::PopMatrix)
+            .map_err(|e| PyRuntimeError::new_err(format!("{e}")))
+    }
+
     #[pyo3(signature = (*args))]
     pub fn translate(&self, args: &Bound<'_, PyTuple>) -> PyResult<()> {
         let v = if args.len() == 3 {

crates/processing_pyo3/src/lib.rs

@@ -990,6 +990,30 @@ mod mewnala {
         graphics!(module).pop_matrix()
     }
 
+    #[pyfunction]
+    #[pyo3(pass_module)]
+    fn push_style(module: &Bound<'_, PyModule>) -> PyResult<()> {
+        graphics!(module).push_style()
+    }
+
+    #[pyfunction]
+    #[pyo3(pass_module)]
+    fn pop_style(module: &Bound<'_, PyModule>) -> PyResult<()> {
+        graphics!(module).pop_style()
+    }
+
+    #[pyfunction]
+    #[pyo3(pass_module)]
+    fn push(module: &Bound<'_, PyModule>) -> PyResult<()> {
+        graphics!(module).push()
+    }
+
+    #[pyfunction]
+    #[pyo3(pass_module)]
+    fn pop(module: &Bound<'_, PyModule>) -> PyResult<()> {
+        graphics!(module).pop()
+    }
+
     #[pyfunction]
     #[pyo3(pass_module, signature = (*args))]
     fn translate(module: &Bound<'_, PyModule>, args: &Bound<'_, PyTuple>) -> PyResult<()> {

crates/processing_render/src/render/command.rs

@@ -573,6 +573,8 @@ pub enum DrawCommand {
     PushMatrix,
     PopMatrix,
     ResetMatrix,
+    PushStyle,
+    PopStyle,
     Translate(Vec3),
     Rotate {
         angle: f32,