DPF

params.h (12910B)

---

 #pragma once
 
 #include "../plugin.h"
 #include "../string-sizes.h"
 
 /// @page Parameters
 /// @brief parameters management
 ///
 /// Main idea:
 ///
 /// The host sees the plugin as an atomic entity; and acts as a controller on top of its parameters.
 /// The plugin is responsible for keeping its audio processor and its GUI in sync.
 ///
 /// The host can at any time read parameters' value on the [main-thread] using
 /// @ref clap_plugin_params.value().
 ///
 /// There are two options to communicate parameter value changes, and they are not concurrent.
 /// - send automation points during clap_plugin.process()
 /// - send automation points during clap_plugin_params.flush(), for parameter changes
 ///   without processing audio
 ///
 /// When the plugin changes a parameter value, it must inform the host.
 /// It will send @ref CLAP_EVENT_PARAM_VALUE event during process() or flush().
 /// If the user is adjusting the value, don't forget to mark the begining and end
 /// of the gesture by sending CLAP_EVENT_PARAM_GESTURE_BEGIN and CLAP_EVENT_PARAM_GESTURE_END
 /// events.
 ///
 /// @note MIDI CCs are tricky because you may not know when the parameter adjustment ends.
 /// Also if the host records incoming MIDI CC and parameter change automation at the same time,
 /// there will be a conflict at playback: MIDI CC vs Automation.
 /// The parameter automation will always target the same parameter because the param_id is stable.
 /// The MIDI CC may have a different mapping in the future and may result in a different playback.
 ///
 /// When a MIDI CC changes a parameter's value, set the flag CLAP_EVENT_DONT_RECORD in
 /// clap_event_param.header.flags. That way the host may record the MIDI CC automation, but not the
 /// parameter change and there won't be conflict at playback.
 ///
 /// Scenarios:
 ///
 /// I. Loading a preset
 /// - load the preset in a temporary state
 /// - call @ref clap_host_params.rescan() if anything changed
 /// - call @ref clap_host_latency.changed() if latency changed
 /// - invalidate any other info that may be cached by the host
 /// - if the plugin is activated and the preset will introduce breaking changes
 ///   (latency, audio ports, new parameters, ...) be sure to wait for the host
 ///   to deactivate the plugin to apply those changes.
 ///   If there are no breaking changes, the plugin can apply them them right away.
 ///   The plugin is resonsible for updating both its audio processor and its gui.
 ///
 /// II. Turning a knob on the DAW interface
 /// - the host will send an automation event to the plugin via a process() or flush()
 ///
 /// III. Turning a knob on the Plugin interface
 /// - the plugin is responsible for sending the parameter value to its audio processor
 /// - call clap_host_params->request_flush() or clap_host->request_process().
 /// - when the host calls either clap_plugin->process() or clap_plugin_params->flush(),
 ///   send an automation event and don't forget to set begin_adjust,
 ///   end_adjust and should_record flags
 ///
 /// IV. Turning a knob via automation
 /// - host sends an automation point during clap_plugin->process() or clap_plugin_params->flush().
 /// - the plugin is responsible for updating its GUI
 ///
 /// V. Turning a knob via plugin's internal MIDI mapping
 /// - the plugin sends a CLAP_EVENT_PARAM_SET output event, set should_record to false
 /// - the plugin is responsible to update its GUI
 ///
 /// VI. Adding or removing parameters
 /// - if the plugin is activated call clap_host->restart()
 /// - once the plugin isn't active:
 ///   - apply the new state
 ///   - if a parameter is gone or is created with an id that may have been used before,
 ///     call clap_host_params.clear(host, param_id, CLAP_PARAM_CLEAR_ALL)
 ///   - call clap_host_params->rescan(CLAP_PARAM_RESCAN_ALL)
 
 static CLAP_CONSTEXPR const char CLAP_EXT_PARAMS[] = "clap.params";
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 enum {
    // Is this param stepped? (integer values only)
    // if so the double value is converted to integer using a cast (equivalent to trunc).
    CLAP_PARAM_IS_STEPPED = 1 << 0,
 
    // Useful for for periodic parameters like a phase
    CLAP_PARAM_IS_PERIODIC = 1 << 1,
 
    // The parameter should not be shown to the user, because it is currently not used.
    // It is not necessary to process automation for this parameter.
    CLAP_PARAM_IS_HIDDEN = 1 << 2,
 
    // The parameter can't be changed by the host.
    CLAP_PARAM_IS_READONLY = 1 << 3,
 
    // This parameter is used to merge the plugin and host bypass button.
    // It implies that the parameter is stepped.
    // min: 0 -> bypass off
    // max: 1 -> bypass on
    CLAP_PARAM_IS_BYPASS = 1 << 4,
 
    // When set:
    // - automation can be recorded
    // - automation can be played back
    //
    // The host can send live user changes for this parameter regardless of this flag.
    //
    // If this parameters affect the internal processing structure of the plugin, ie: max delay, fft
    // size, ... and the plugins needs to re-allocate its working buffers, then it should call
    // host->request_restart(), and perform the change once the plugin is re-activated.
    CLAP_PARAM_IS_AUTOMATABLE = 1 << 5,
 
    // Does this parameter support per note automations?
    CLAP_PARAM_IS_AUTOMATABLE_PER_NOTE_ID = 1 << 6,
 
    // Does this parameter support per key automations?
    CLAP_PARAM_IS_AUTOMATABLE_PER_KEY = 1 << 7,
 
    // Does this parameter support per channel automations?
    CLAP_PARAM_IS_AUTOMATABLE_PER_CHANNEL = 1 << 8,
 
    // Does this parameter support per port automations?
    CLAP_PARAM_IS_AUTOMATABLE_PER_PORT = 1 << 9,
 
    // Does this parameter support the modulation signal?
    CLAP_PARAM_IS_MODULATABLE = 1 << 10,
 
    // Does this parameter support per note modulations?
    CLAP_PARAM_IS_MODULATABLE_PER_NOTE_ID = 1 << 11,
 
    // Does this parameter support per key modulations?
    CLAP_PARAM_IS_MODULATABLE_PER_KEY = 1 << 12,
 
    // Does this parameter support per channel modulations?
    CLAP_PARAM_IS_MODULATABLE_PER_CHANNEL = 1 << 13,
 
    // Does this parameter support per port modulations?
    CLAP_PARAM_IS_MODULATABLE_PER_PORT = 1 << 14,
 
    // Any change to this parameter will affect the plugin output and requires to be done via
    // process() if the plugin is active.
    //
    // A simple example would be a DC Offset, changing it will change the output signal and must be
    // processed.
    CLAP_PARAM_REQUIRES_PROCESS = 1 << 15,
 };
 typedef uint32_t clap_param_info_flags;
 
 /* This describes a parameter */
 typedef struct clap_param_info {
    // stable parameter identifier, it must never change.
    clap_id id;
 
    clap_param_info_flags flags;
 
    // This value is optional and set by the plugin. The host will
    // set it on all subsequent events regarding this param_id 
    // or set the cookie to nullptr if the host chooses to
    // not implement cookies. 
    //
    // The plugin must gracefully handle the case of a cookie 
    // which is nullptr, but can safely assume any cookie 
    // which is not nullptr is the value it issued.
    // 
    // It is very strongly recommended that the host implement 
    // cookies. Some plugins may have noticably reduced
    // performance when addressing params in hosts without cookies.
    //
    // The cookie's purpose is to provide a fast access to the 
    // plugin parameter objects. For instance:
    //
    // in clap_plugin_params.get_info
    //    Parameter *p = findParameter(param_id);
    //    param_info->cookie = p;
    //
    // later, in clap_plugin.process:
    //
    //    Parameter *p{nullptr};
    //    if (evt->cookie) [[likely]]
    //       p =  (Parameter *)evt->cookie;
    //    else
    //       p = -- alternate mechanism --
    //
    // where "alternate mechanism" is a mechanism the plugin implements
    // to map parameter ids to internal objects. 
    //
    // The host should make no assumption about the
    // value of the cookie other than passing it back to the plugin or
    // replacing it with nullptr. 
    //
    // Once set, the cookie is valid until invalidated by a call to 
    // clap_host_params->rescan(CLAP_PARAM_RESCAN_ALL) or when the plugin is
    // destroyed.
    void *cookie;
 
    // the display name
    char name[CLAP_NAME_SIZE];
 
    // the module path containing the param, eg:"oscillators/wt1"
    // '/' will be used as a separator to show a tree like structure.
    char module[CLAP_PATH_SIZE];
 
    double min_value;     // minimum plain value
    double max_value;     // maximum plain value
    double default_value; // default plain value
 } clap_param_info_t;
 
 typedef struct clap_plugin_params {
    // Returns the number of parameters.
    // [main-thread]
    uint32_t(CLAP_ABI *count)(const clap_plugin_t *plugin);
 
    // Copies the parameter's info to param_info and returns true on success.
    // [main-thread]
    bool(CLAP_ABI *get_info)(const clap_plugin_t *plugin,
                             uint32_t             param_index,
                             clap_param_info_t   *param_info);
 
    // Gets the parameter plain value.
    // [main-thread]
    bool(CLAP_ABI *get_value)(const clap_plugin_t *plugin, clap_id param_id, double *value);
 
    // Formats the display text for the given parameter value.
    // The host should always format the parameter value to text using this function
    // before displaying it to the user.
    // [main-thread]
    bool(CLAP_ABI *value_to_text)(
       const clap_plugin_t *plugin, clap_id param_id, double value, char *display, uint32_t size);
 
    // Converts the display text to a parameter value.
    // [main-thread]
    bool(CLAP_ABI *text_to_value)(const clap_plugin_t *plugin,
                                  clap_id              param_id,
                                  const char          *display,
                                  double              *value);
 
    // Flushes a set of parameter changes.
    // This method must not be called concurrently to clap_plugin->process().
    //
    // Note: if the plugin is processing, then the process() call will already achieve the
    // parameter update (bi-directionnal), so a call to flush isn't required, also be aware
    // that the plugin may use the sample offset in process(), while this information would be
    // lost within flush().
    //
    // [active ? audio-thread : main-thread]
    void(CLAP_ABI *flush)(const clap_plugin_t        *plugin,
                          const clap_input_events_t  *in,
                          const clap_output_events_t *out);
 } clap_plugin_params_t;
 
 enum {
    // The parameter values did change, eg. after loading a preset.
    // The host will scan all the parameters value.
    // The host will not record those changes as automation points.
    // New values takes effect immediately.
    CLAP_PARAM_RESCAN_VALUES = 1 << 0,
 
    // The value to text conversion changed, and the text needs to be rendered again.
    CLAP_PARAM_RESCAN_TEXT = 1 << 1,
 
    // The parameter info did change, use this flag for:
    // - name change
    // - module change
    // - is_periodic (flag)
    // - is_hidden (flag)
    // New info takes effect immediately.
    CLAP_PARAM_RESCAN_INFO = 1 << 2,
 
    // Invalidates everything the host knows about parameters.
    // It can only be used while the plugin is deactivated.
    // If the plugin is activated use clap_host->restart() and delay any change until the host calls
    // clap_plugin->deactivate().
    //
    // You must use this flag if:
    // - some parameters were added or removed.
    // - some parameters had critical changes:
    //   - is_per_note (flag)
    //   - is_per_channel (flag)
    //   - is_readonly (flag)
    //   - is_bypass (flag)
    //   - is_stepped (flag)
    //   - is_modulatable (flag)
    //   - min_value
    //   - max_value
    //   - cookie
    CLAP_PARAM_RESCAN_ALL = 1 << 3,
 };
 typedef uint32_t clap_param_rescan_flags;
 
 enum {
    // Clears all possible references to a parameter
    CLAP_PARAM_CLEAR_ALL = 1 << 0,
 
    // Clears all automations to a parameter
    CLAP_PARAM_CLEAR_AUTOMATIONS = 1 << 1,
 
    // Clears all modulations to a parameter
    CLAP_PARAM_CLEAR_MODULATIONS = 1 << 2,
 };
 typedef uint32_t clap_param_clear_flags;
 
 typedef struct clap_host_params {
    // Rescan the full list of parameters according to the flags.
    // [main-thread]
    void(CLAP_ABI *rescan)(const clap_host_t *host, clap_param_rescan_flags flags);
 
    // Clears references to a parameter.
    // [main-thread]
    void(CLAP_ABI *clear)(const clap_host_t *host, clap_id param_id, clap_param_clear_flags flags);
 
    // Request a parameter flush.
    //
    // The host will then schedule a call to either:
    // - clap_plugin.process()
    // - clap_plugin_params.flush()
    //
    // This function is always safe to use and should not be called from an [audio-thread] as the
    // plugin would already be within process() or flush().
    //
    // [thread-safe,!audio-thread]
    void(CLAP_ABI *request_flush)(const clap_host_t *host);
 } clap_host_params_t;
 
 #ifdef __cplusplus
 }
 #endif