/** * Initiates zoom in one dimension. * * This method modifies Graph.downLocation. * * @param {Event} event event * @param {number} width width, in pixels * @param {number} height height, in pixels * @param {Box} margin margin * @param {Box} padding padding * @param {boolean} isDragging true iff dragging is supported in both X and Y dimensions * @param {number} xScrollSize scroll size in the X dimension, or <0 if not supported, or 0 for default * @param {number} yScrollSize scroll size in the Y dimension, or <0 if not supported, or 0 for default * @param {D3Scale} xScale X scale * @param {D3Scale} yScale Y scale * @param {Array} xDomain0 Initial X domain * @param {Array} yDomain0 Initial Y domain */ Graph.onPointerDown = ( event, width, height, margin, padding, isDragging, xScrollSize, yScrollSize, xScale, yScale, xDomain0, yDomain0 ) => { // Initialization. const scrollSize = (( event.pointerType === "touch" ) ? 2 : 1 ) * Graph.scrollSize, endCapSize = 0.8 * scrollSize; let top = margin.top + padding.top, right = margin.right + padding.right, bottom = margin.bottom + padding.bottom, left = margin.left + padding.left, xDomain = xScale.domain(), yDomain = yScale.domain(), { xMin0, xMax0, yMin0, yMax0, xMin, xMax, yMin, yMax, xD, yD } = Graph.getDomains( xDomain0, yDomain0, xDomain, yDomain, !!xScale.bandwidth, !!yScale.bandwidth ); let xDown, yDown; if( event.touches ) { const touch = event.touches[ 0 ]; xDown = touch.clientX - event.currentTarget.getBoundingClientRect().x; yDown = touch.clientY - event.currentTarget.getBoundingClientRect().y; } else { xDown = event.offsetX; yDown = event.offsetY; } // Reset the mousedown coordinates. Graph.downLocation.x = xDown; Graph.downLocation.y = yDown; Graph.downLocation.xDomain = []; Graph.downLocation.yDomain = []; Graph.downLocation.isX = false; Graph.downLocation.isY = false; Graph.downLocation.isMin = false; Graph.downLocation.isMax = false; // Stop propagation to document. event.stopPropagation(); // Handle event on X scrollbar... if(( left <= xDown ) && ( xDown <= width - right ) && ( height - ( xScrollSize ? xScrollSize : scrollSize ) <= yDown ) && ( yDown <= height )) { let w = width - right - left + 1, x0 = left + w * ( xMin - xMin0 ) / ( xMax0 - xMin0 + xD ), x1 = left + w * ( xMax - xMin0 + xD ) / ( xMax0 - xMin0 + xD ); if( event.preventDefault ) { event.preventDefault(); } Graph.downLocation.xDomain = xScale.domain(); Graph.downLocation.isX = true; if(( x0 <= xDown ) && ( xDown <= x0 + endCapSize )) { Graph.downLocation.isMin = true; } else if(( x1 - endCapSize <= xDown ) && ( xDown <= x1 )) { Graph.downLocation.isMax = true; } } // ...or handle event on Y scrollbar... else if(( 0 <= xDown ) && ( xDown <= scrollSize ) && ( top <= yDown ) && ( yDown <= height - bottom )) { let h = height - bottom - top + 1, y0 = top + h * ( 1 - ( yMin - yMin0 ) / ( yMax0 - yMin0 + yD )), y1 = top + h * ( 1 - ( yMax - yMin0 + yD ) / ( yMax0 - yMin0 + yD )); if( event.preventDefault ) { event.preventDefault(); } Graph.downLocation.yDomain = yScale.domain(); Graph.downLocation.isY = true; if(( y1 <= yDown ) && ( yDown <= y1 + endCapSize )) { Graph.downLocation.isMax = true; } else if(( y0 - endCapSize <= yDown ) && ( yDown <= y0 )) { Graph.downLocation.isMin = true; } } };