Add mini-curve-display-hints extension.

This extension allows the plugin to optionally query the host for hints
as to how a curve of a certain kind will be displayed.

Author: roelofvkr

include/clap/all.h

@@ -8,6 +8,7 @@
 #include "ext/draft/extensible-audio-ports.h"
 #include "ext/draft/gain-adjustment-metering.h"
 #include "ext/draft/mini-curve-display.h"
+#include "ext/draft/mini-curve-display-hints.h"
 #include "ext/draft/project-location.h"
 #include "ext/draft/resource-directory.h"
 #include "ext/draft/scratch-memory.h"

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

@@ -0,0 +1,69 @@
+#pragma once
+
+#include "../../plugin.h"
+
+// This extension can be optionally provided by a host as an addition to clap.mini-curve-display
+// in order to give the plugin more knowledge about how the mini curve display will be
+// displayed.
+
+static CLAP_CONSTEXPR const char CLAP_EXT_MINI_CURVE_DISPLAY_HINTS[] =
+   "clap.mini-curve-display-hints/1";
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum clap_mini_curve_display_curve_kind {
+   // 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).
+   // 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).
+   // This would be useful in for example an equalizer.
+   CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_PHASE_RESPONSE = 2,
+
+   // The mini curve is intended to draw the transfer curve of the plugin.
+   // In this case the both x and y values are in dB.
+   // This would be useful in for example a compressor or distortion plugin.
+   CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_TRANSFER_CURVE = 3,
+
+   // This mini curve is intended to draw gain reduction over time. In this case
+   // x refers to the window in seconds and y refers to level in dB, x_min is
+   // always 0, and x_max would be the duration of the window.
+   // This would be useful in for example a compressor or limiter.
+   CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_GAIN_REDUCTION = 4,
+
+   // This curve is intended as a generic time series plot. In this case
+   // x refers to the window in seconds. x_min is always 0, and x_max would be the duration of the
+   // window.
+   // Y is not specified and up to the plugin.
+   CLAP_MINI_CURVE_DISPLAY_CURVE_KIND_TIME_SERIES = 5,
+};
+
+typedef struct clap_mini_display_curve_hints {
+
+   // Range for the x axis.
+   double x_min;
+   double x_max;
+
+   // Range for the y axis.
+   double y_min;
+   double y_max;
+
+} clap_mini_display_curve_hints_t;
+
+typedef struct clap_host_mini_curve_display_hints {
+   // Fills in the given clap_mini_display_curve_hints_t structure and returns
+   // 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);
+} clap_host_mini_curve_display_hints_t;
+
+#ifdef __cplusplus
+}
+#endif
+