func (c *Context) PopLayer() {
	if c.layerStack == nil || len(c.layerStack.layers) == 0 {
		return
	}

	// Pop the current layer
	layers := c.layerStack.layers
	layer := layers[len(layers)-1]
	c.layerStack.layers = layers[:len(layers)-1]

	// Get parent pixmap (either previous layer or base)
	var parentPixmap *Pixmap
	if len(c.layerStack.layers) > 0 {
		parentPixmap = c.layerStack.layers[len(c.layerStack.layers)-1].pixmap
	} else {
		// Restore base pixmap
		parentPixmap = c.basePixmap
		c.basePixmap = nil
	}

	// Apply mask to layer content before compositing (PushMaskLayer).
	if layer.mask != nil {
		c.applyMaskToPixmap(layer.pixmap, layer.mask)
	}

	// Composite layer onto parent
	c.compositeLayer(layer, parentPixmap)

	// Restore parent pixmap as current drawing target
	c.pixmap = parentPixmap
}

func (c *Context) PushLayer(blendMode BlendMode, opacity float64) {
	// Clamp opacity to valid range
	if opacity < 0 {
		opacity = 0
	}
	if opacity > 1 {
		opacity = 1
	}

	// Initialize layer stack if needed
	if c.layerStack == nil {
		c.layerStack = newLayerStack()
	}

	// Save base pixmap on first push
	if len(c.layerStack.layers) == 0 && c.basePixmap == nil {
		c.basePixmap = c.pixmap
	}

	// Create new pixmap for the layer (same size as context)
	layerPixmap := NewPixmap(c.width, c.height)
	layerPixmap.Clear(Transparent)

	// Create layer
	layer := &Layer{
		pixmap:		layerPixmap,
		blendMode:	blendMode,
		opacity:	opacity,
	}

	// Save current pixmap and switch to layer pixmap
	c.layerStack.layers = append(c.layerStack.layers, layer)
	c.pixmap = layerPixmap
}

func (c *Context) PushMaskLayer(mask *Mask) {
	// Clamp: nil mask means no masking (equivalent to PushLayer).
	if mask == nil {
		c.PushLayer(BlendNormal, 1.0)
		return
	}

	// Initialize layer stack if needed.
	if c.layerStack == nil {
		c.layerStack = newLayerStack()
	}

	// Save base pixmap on first push.
	if len(c.layerStack.layers) == 0 && c.basePixmap == nil {
		c.basePixmap = c.pixmap
	}

	// Create new pixmap for the layer (same size as context).
	layerPixmap := NewPixmap(c.width, c.height)
	layerPixmap.Clear(Transparent)

	// Create layer with mask.
	layer := &Layer{
		pixmap:		layerPixmap,
		blendMode:	BlendNormal,
		opacity:	1.0,
		mask:		mask,
	}

	// Switch to layer pixmap.
	c.layerStack.layers = append(c.layerStack.layers, layer)
	c.pixmap = layerPixmap
}

func (c *Context) SetBlendMode(_ BlendMode) {
	// Store for future use in paint operations
	// Currently, blending is primarily done via layers
}

type Layer struct {
	pixmap		*Pixmap
	blendMode	BlendMode
	opacity		float64
	mask		*Mask	// optional alpha mask, applied on PopLayer (nil = no mask)
}