mini-curve-display: support stacked mini curves

include/clap/ext/draft/mini-curve-display.h

@@ -54,14 +54,28 @@ typedef struct clap_mini_display_curve_hints {
 
 } clap_mini_display_curve_hints_t;
 
-
 typedef struct clap_plugin_mini_curve_display {
+   // Returns the number of curves the plugin wants to paint.
+   // Be aware that the space to display those curves will be small, and too much data will make
+   // the output hard to read.
+   uint32_t(CLAP_ABI *get_curve_count)(const clap_plugin_t *plugin);
+
    // Renders the curve into the data buffer.
-   // The value 0 will be at the bottom of the curve and UINT16_MAX will be at the top.
-   // The value at index 0 will be the leftmost and the value at index data_size -1 will be the
-   // rightmost.
+   //
+   // The host will "stack" the curves, from the first one to the last one.
+   // data[0] is the first curve to be painted.
+   // data[n + 1] will be painted over data[n].
+   // The data[n][0] will be the leftmost value and data[n][data_size -1] will be the rightmost
+   // value.
+   //
+   // The value 0 and UINT16_MAX won't be painted.
+   // The value 1 will be at the bottom of the curve and UINT16_MAX - 1 will be at the top.
+   //
    // [main-thread]
-   bool(CLAP_ABI *render)(const clap_plugin_t *plugin, uint16_t *data, uint32_t data_size);
+   bool(CLAP_ABI *render)(const clap_plugin_t *plugin,
+                          uint32_t             curve_count,
+                          uint16_t *const     *data,
+                          uint32_t             data_size);
 
    // Tells the plugin if the curve is currently observed or not.
    // When it isn't observed render() can't be called.
@@ -97,8 +111,8 @@ typedef struct clap_host_mini_curve_display {
    // true if succesful. If not, return false.
    // [main-thread]
    bool(CLAP_ABI *get)(const clap_host_t               *host,
-      uint32_t                         kind,
-      clap_mini_display_curve_hints_t *hints);
+                       uint32_t                         kind,
+                       clap_mini_display_curve_hints_t *hints);
 
    // Mark the curve as being static or dynamic.
    // The curve is initially considered as static, though the plugin should explicitely