/** @packageDocumentation
 * @module WebGL
 */
import { StopWatch } from "@itwin/core-bentley";
import { GLTimerResultCallback } from "../RenderSystemDebugControl";
import { FrameBuffer } from "./FrameBuffer";
/** @internal */
export declare class PerformanceMetrics {
    private _beginTimePoints;
    private _operationNames;
    private _allTimePoints1;
    private _allTimePoints2;
    private _updateallTimePoints1;
    frameTimings: Map<string, number>;
    gatherGlFinish: boolean;
    gatherCurPerformanceMetrics: boolean;
    curSpfTimeIndex: number;
    spfTimes: number[];
    spfSum: number;
    fpsTimer: StopWatch;
    fpsTimerStart: number;
    constructor(gatherGlFinish?: boolean, gatherCurPerformanceMetrics?: boolean, gpuResults?: GLTimerResultCallback);
    beginFrame(sceneTime?: number): void;
    beginOperation(operationName: string): void;
    endOperation(): void;
    endFrame(): void;
    completeFrameTimings(fbo: FrameBuffer): void;
}
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