mini-curve-display: support stacked mini curves

Author: abique

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

@@ -5,20 +5,24 @@
 // This extension allows a host to render a small curve provided by the plugin.
 // A useful application is to render an EQ frequency response in the DAW mixer view.
 
-static CLAP_CONSTEXPR const char CLAP_EXT_MINI_CURVE_DISPLAY[] = "clap.mini-curve-display/2";
+static CLAP_CONSTEXPR const char CLAP_EXT_MINI_CURVE_DISPLAY[] = "clap.mini-curve-display/3";
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 enum clap_mini_curve_display_curve_kind {
+   // If the curve's kind doesn't fit in any proposed kind, use this one
+   // and perhaps, make a pull request to extend the list.
+   CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_UNSPECIFIED = 0,
+
    // The mini curve is intended to draw the total gain response of the plugin.
-   // In this case the y values are in dB and the x values are in hz (logarithmic).
+   // In this case the y values are in dB and the x values are in Hz (logarithmic).
    // This would be useful in for example an equalizer.
    CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_GAIN_RESPONSE = 1,
 
    // The mini curve is intended to draw the total phase response of the plugin.
-   // In this case the y values are in radians and the x values are in hz (logarithmic).
+   // In this case the y values are in radians and the x values are in Hz (logarithmic).
    // This would be useful in for example an equalizer.
    CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_PHASE_RESPONSE = 2,
 
@@ -42,7 +46,7 @@ enum clap_mini_curve_display_curve_kind {
    // Note: more entries could be added here in the future
 };
 
-typedef struct clap_mini_display_curve_hints {
+typedef struct clap_mini_curve_display_curve_hints {
 
    // Range for the x axis.
    double x_min;
@@ -52,21 +56,48 @@ typedef struct clap_mini_display_curve_hints {
    double y_min;
    double y_max;
 
-} clap_mini_display_curve_hints_t;
+} clap_mini_curve_display_curve_hints_t;
+
+// A set of points representing the curve to be painted.
+typedef struct clap_mini_curve_display_curve_data {
+   // Indicates the kind of curve those values represent, the host can use this
+   // information to paint the curve using a meaningful color.
+   int32_t curve_kind;
 
+   // values[0] will be the leftmost value and values[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.
+   uint16_t *values;
+   uint32_t  values_count;
+} clap_mini_curve_display_curve_data_t;
 
 typedef struct clap_plugin_mini_curve_display {
-   // 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.
+   // 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 each the curves buffer.
+   //
+   // curves is an array, and each entries (up to curves_size) contains pre-allocated
+   // values buffer that must be filled by the plugin.
+   //
+   // The host will "stack" the curves, from the first one to the last one.
+   // curves[0] is the first curve to be painted.
+   // curves[n + 1] will be painted over curves[n].
+   //
+   // Returns the number of curves rendered.
    // [main-thread]
-   bool(CLAP_ABI *render)(const clap_plugin_t *plugin, uint16_t *data, uint32_t data_size);
+   uint32_t(CLAP_ABI *render)(const clap_plugin_t                  *plugin,
+                              clap_mini_curve_display_curve_data_t *curves,
+                              uint32_t                              curves_size);
 
    // Tells the plugin if the curve is currently observed or not.
    // When it isn't observed render() can't be called.
    //
-   // When is_obseverd becomes true, the curve content and axis name are implicitely invalidated. So
+   // When is_obseverd becomes true, the curve content and axis name are implicitly invalidated. So
    // the plugin don't need to call host->changed.
    //
    // [main-thread]
@@ -77,6 +108,7 @@ typedef struct clap_plugin_mini_curve_display {
    // Returns true on success, if the name capacity was sufficient.
    // [main-thread]
    bool(CLAP_ABI *get_axis_name)(const clap_plugin_t *plugin,
+                                 uint32_t             curve_index,
                                  char                *x_name,
                                  char                *y_name,
                                  uint32_t             name_capacity);
@@ -94,11 +126,11 @@ enum clap_mini_curve_display_change_flags {
 
 typedef struct clap_host_mini_curve_display {
    // Fills in the given clap_mini_display_curve_hints_t structure and returns
-   // true if succesful. If not, return false.
+   // true if successful. 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);
+   bool(CLAP_ABI *get_hints)(const clap_host_t                     *host,
+                             uint32_t                               kind,
+                             clap_mini_curve_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