A driver integrated circuit, hereinafter driver IC, connectable to a touch display panel and adapted to selectively operate in a display mode, a self-capacitor mode and a mutual-capacitor mode when the driver IC is coupled to the touch display panel, wherein the driver IC is adapted so that when it operates in the display mode, the driver IC outputs display data to a plurality of source lines of the touch display panel; the driver IC is adapted so that when it operates in the self-capacitor mode, the driver controls the source lines to have a predetermined voltage; and the driver IC is adapted so that when it operates in the mutual-capacitor mode, the driver IC sequentially sends an impulse signal to the source lines; wherein the driver integrated circuit comprises a multiplexing circuit, a common voltage source, an analog processing circuit, and a buffer; wherein a common voltage layer of the touch display panel comprises a plurality of vertical sections (COMV 1 - COMV m) and a plurality of horizontal sections (COMH 1 - COMH m), wherein each of the plurality of vertical sections (COMV 1 - COMV m) comprises two vertical segments (COMV 11, COMV 12) and each of the plurality of horizontal sections (COMH 1 - COMH m) comprises a plurality of horizontal segments, wherein the segments of the plurality of horizontal segments of each horizontal section that are arranged in one horizontal row are connected together via a metal layer disposed above the common voltage layer to constitute a horizontal set (HS 1 - HS n), wherein the plurality of vertical segments is a first section of the common lines of the touch display panel and the plurality of horizontal sets is a second section of the common lines of the touch display panel, wherein a second metal layer underneath the common voltage layer comprises the plurality of source lines, and a first metal layer underneath the second metal layer comprises the plurality of gate lines, each source line substantially corresponds to one of the plurality of vertical segments or one of the plurality of horizontal sections, and the plurality of source lines and the plurality of gate lines are intersected; and the driver IC is adapted so that when it operates in the display mode, the driver IC controls common lines of the touch display panel to have a common voltage, wherein the multiplexing circuit is arranged to control the common voltage layer, i.e. the plurality of vertical segments and the plurality of horizontal sections, to have the common voltage provided by the common voltage source, and the multiplexing circuit is arranged to send the display data stored in the buffer to the plurality of source lines; the driver IC is adapted so that when it operates in the self-capacitor mode, the driver IC controls one section of the first section and the second section of the common lines to be floating or to have a reference voltage together with a plurality of gate lines and transmits the signals of the other section of the first section and the second section of the common lines via the multiplexing circuit to the analog processing circuit for detection of capacitance variation; and the driver IC is adapted so that when it operates in the mutual-capacitor mode, driver IC controls the first section of the common lines to be sequentially floating, wherein non-floating vertical segments are connected to a reference voltage, wherein the multiplexing circuit is adapted so that it sends the impulse signal generated by an impulse signal generator to the source line corresponding to the floating vertical segment, wherein the signals of the plurality of horizontal sets are sent to the analog processing circuit via the multiplexing circuit.