Initial QSfera import

Server/vendor/github.com/davidbyttow/govips/v2/vips/logging.go

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+package vips
+
+// #include <glib.h>
+import "C"
+import (
+	"log"
+)
+
+// LogLevel is the enum controlling logging message verbosity.
+type LogLevel int
+
+// The logging verbosity levels classify and filter logging messages.
+// From most to least verbose, they are debug, info, message, warning, critical and error.
+const (
+	LogLevelError    LogLevel = C.G_LOG_LEVEL_ERROR
+	LogLevelCritical LogLevel = C.G_LOG_LEVEL_CRITICAL
+	LogLevelWarning  LogLevel = C.G_LOG_LEVEL_WARNING
+	LogLevelMessage  LogLevel = C.G_LOG_LEVEL_MESSAGE
+	LogLevelInfo     LogLevel = C.G_LOG_LEVEL_INFO
+	LogLevelDebug    LogLevel = C.G_LOG_LEVEL_DEBUG
+)
+
+// Three global variables which keep state of the current logging handler
+// function, desired verbosity for logging and whether defaults have been
+// overridden. Set by LoggingSettings()
+var (
+	currentLoggingHandlerFunction LoggingHandlerFunction
+	currentLoggingVerbosity       LogLevel
+	currentLoggingOverridden      bool
+)
+
+// govipsLoggingHandler is the private bridge function exported to the C library
+// and called by glib and libvips for each logging message. It will call govipsLog
+// which in turn will filter based on verbosity and direct the messages to the
+// currently chosen LoggingHandlerFunction.
+//
+//export govipsLoggingHandler
+func govipsLoggingHandler(messageDomain *C.char, messageLevel C.int, message *C.char) {
+	govipsLog(C.GoString(messageDomain), LogLevel(messageLevel), C.GoString(message))
+}
+
+// LoggingHandlerFunction is a function which will be called for each log message.
+// By default, govips sends logging messages to os.Stderr. If you want to log elsewhere
+// such as to a file or to a state variable which you inspect yourself, define a new
+// logging handler function and set it via LoggingSettings().
+type LoggingHandlerFunction func(messageDomain string, messageLevel LogLevel, message string)
+
+// LoggingSettings sets the logging handler and logging verbosity for govips.
+// The handler function is the function which will be called for each log message.
+// You can define one yourself to log somewhere else besides the default (stderr).
+// Use nil as handler to use standard logging handler.
+// Verbosity is the minimum logLevel you want to log. Default is logLevelInfo
+// due to backwards compatibility but it's quite verbose for a library.
+// Suggest setting it to at least logLevelWarning. Use logLevelDebug for debugging.
+func LoggingSettings(handler LoggingHandlerFunction, verbosity LogLevel) {
+	currentLoggingOverridden = true
+	govipsLoggingSettings(handler, verbosity)
+}
+
+func govipsLoggingSettings(handler LoggingHandlerFunction, verbosity LogLevel) {
+	if handler == nil {
+		currentLoggingHandlerFunction = defaultLoggingHandlerFunction
+	} else {
+		currentLoggingHandlerFunction = handler
+	}
+
+	currentLoggingVerbosity = verbosity
+	// TODO turn on debugging in libvips and redirect to handler when setting verbosity to debug
+	// This way debugging information would go to the same channel as all other logging
+}
+
+func defaultLoggingHandlerFunction(messageDomain string, messageLevel LogLevel, message string) {
+	var messageLevelDescription string
+	switch messageLevel {
+	case LogLevelError:
+		messageLevelDescription = "error"
+	case LogLevelCritical:
+		messageLevelDescription = "critical"
+	case LogLevelWarning:
+		messageLevelDescription = "warning"
+	case LogLevelMessage:
+		messageLevelDescription = "message"
+	case LogLevelInfo:
+		messageLevelDescription = "info"
+	case LogLevelDebug:
+		messageLevelDescription = "debug"
+	}
+
+	log.Printf("[%v.%v] %v", messageDomain, messageLevelDescription, message)
+}
+
+// govipsLog is the default function used to log debug or error messages internally in govips.
+// It's used by all govips functionality directly, as well as by glib and libvips via the C bridge.
+func govipsLog(messageDomain string, messageLevel LogLevel, message string) {
+	if messageLevel <= currentLoggingVerbosity {
+		currentLoggingHandlerFunction(messageDomain, messageLevel, message)
+	}
+}